l.irl;---------~-----~--------'-'-======__..~iiiiii,........~=======I, 1 . ../"

'I

i J 'I the distribution of GBD I Americans. As newcomer I

States, Mexican Americam

Country of Birth and Prevalence of Gallbladder Disease in are less well-integrated int< culture than are those hOI

Mexican Americans States; Mexico-born MeJ< are less likely to speak En!

Marilyn Tseng, PhD; Robert Millikan, DVM, MPH, PhD; Kurt R. Maurer, PhD; Meena to have residential contac Khare, MS; James E. Everhart, MD, MPH; Robert S. Sandler, MD, MPH panic whites, to warry 01

ethnic group, and to enjo: Objectives. This research sought to describe the association between country of birth success. 7

and gallbladder disease (GBD) in Mexican Americans, identify subgroups at especially high risk, and identify risk factors that may mediate a birthplace-GBD association.

Design. Cross-sectional. Methods. Our study population included 4157 Mexican Americans aged 20-74 who

participated in the 1988-94 third National Health and Nutrition Examination Survey. GBD

The social, cultural, an ferences between Mexic( Mexican Americans are differences in health-relat(

was diagnosed by ultrasound. Information on country of birth, education, income, and health outcomes, including selected GBD risk factors was obtained from interviews. Prevalence odds ratios (POR) for GBD in Mexico­ vs US-born Mexican Americans were estimated by unconditional logistic regression, along with 95% confidence intervals (CI). To evaluate the extent to which GBD risk factors mediated the birthplace-GBD association, PORs for country of birth were compared in models with and without additional covariates.

take,9.IO birth weight,'1.12 a

and age-adjusted l4 mortalit GBD prevalence accordin birth in Mexican AmeriCa!

Results. Age-adjusted GBD prevalence was lower in Mexico- than in US-born Mexican­ previously investigated. American women (POR = 0:70, 95% CI 0.50, 0.98) and men (POR = 0.63, 95% CI We used data from th

~

0.40, 0.97). The difference was especially pronounced among subjects of lower socio­economic status. Despite substantial differences in GBD risk factor distributions by birth­place, none could completely explain the prevalence difference.

Conclusions. The observation that GBD prevalence is higher among US-born Mexican

I • Health and Nutrition Exa (NHANES III) to describl between country of birth a

! Americans is consistent with research showing poorer health in this group. Further re­search is needed to identify strategies for reducing morbidity from GBD in Mexican Amer­icans. (Ethn Dis. 2000;10:96-105)

ican Americans, to identify population ,at especially t disease, and to identify ris1

" Key Words: Immigration

Cholelithiasis, Mexican Americans, Socioeconomic Factors, Emigration, mediate a birthplace-GBD

Methods

Introduction morbidity, affecting an estimated 20 million , Study popula

Gallbladder disease (GBD), defined as either having gallstones or having had sur­gery for gallstones, is a common source of

people in the United States. While most cases are asymptomatic, over 500,000 cho­lecystectomies are performed and over 800,000 people are hospitalized annually

NHANES Ill, a cross­conducted between 1988 ar a complex, four-stage prol scheme designed to repres.

I, ! I , . .

From the Department of Epidemiology, University of North Carolina at Chapel Hill, NC [MT, RM]; National Center for Health Statistics, Hyattsville, MD [KRM,

because of gallstones. I The burden of morbidity from GBD is

not shared equally. GBD occurs dispropor­

civilian non-institutionalize the age of two months. IS

cans were oversampled to I

MK]; National Institute of Diabetes and Digestive and tionately in Native and Mexican Ameri­ third of the survey popu Kidney Diseases, Bethesda, MD [JEE]; Department of Medicine, University of North Carolina at Chapel Hill, NC [RSS].

Address correspondence and reprint requests to: Marilyn Tseng, PhD; Division of Population Science;

cans, and especially in Native- and Mexi­can-American women.2,3 The disproportion­ate occurrence of GBD in the Mexican­American population has been attributed to

American ethnicity was s· vey participants were inte in either English or Spanisl ly underwent a physical e>

Fox Chase Cancer Center; 7701 Burholme Avenue; genetic susceptibility.4-6 However, social, and health interview, and , Philadelphia, PA 19111. 215-728-5677,215-728-3574 economic, and cultural heterogeneity in this tests at a Mobile Exar (fax); e-mail: m_tseng@fccc.edu population may have important effects on (MEC).

j

I

I'

dder Disease in

l. Maurer, PhD; Meena mdler, MD, MPH

~tween country of birth Jbgroups at especially ,BO association.

:ans aged 20-74 who mination Survey. GBO jucation, income, and lce odds ratios (paR) lated by unconditional evaluate the extent to I, paRs for country of :ltes. .n in US-born Mexican­paR = 0.63, 95% CI Jbjects of lower socio­f distributions by birth­

lOng US-born Mexican this group. Further re­3BO in Mexican Amer­

~ Factors, Emigration,

ting an estimated 20 million Jnited States. While most Itomatic, over 500,000 cho­are performed and over are hospitalized annually

.tones. I )f morbidity from GBD is lly. GBD occurs dispropor­ltive and Mexican Ameri­ially in Native- and Mexi­romen.2.3 The disproportion­of GBD in the Mexican­ation has been attributed to ibility.4-6 However, social, :ultural heterogeneity in this,

have important effects o'll

\1 Country of Birth and Gallbladder Disease---Tseng et al 97

the distribution of GBD among Mexican Country-oj-birth and other covariates Americans. As newcomers to the United States, Mexican Americans born in Mexico are less well-integrated into mainstream US culture than are those born in the United States; Mexico-born Mexican Americans are less likely to speak English proficiently, to have residential contact with non-His­panic whites, to warry outside their own ethnic group, and to enjoy socioeconomic s~ccess.7

Interview data included information on country of birth (US, Mexico, or other), age, highest grade completed, family in­come, and (for individuals not born in the United States), length of residence in the United States. Age at immigration was es­timated for Mexico-born Mexican Ameri­cans as the difference between age at inter­view and length of residence in the United

II

,

. The social, cultural, and economic dif­ferences between Mexico- and US-born Mexican Americans are accompanied by differences in health-related behaviors and health outcomes, including diet,S alcohol in­take,9.IO birth weight,II.12 and age-specific 13

and age-adjusted l4 mortality. Differences in GBD prevalence according to country of birth in Mexican Americans have not been

States. Proportion of life lived in the United States was also estimated for Mexico-born Mexican Americans by dividing length of residence in the United States by age at in­terview. Information on length of residence, age at immigration, and proportion of life lived in the United States was not available for 296 of the 2,344 Mexico-born Mexican Americans.

previously investigated. We used data from the third National

Grade completion was dichotomized as 0-11 and ~12 to ensure adequate numbers

Health and Nutrition Examination Survey (NHANES III) to describe the association between country of birth and GBD in Mex­ican Americans, to identify the subset of the population at especially high risk for the disease, and to identify risk factors that may mediate a birthplace-GBD association.

in stratified analyses. Poverty-income ratio (PIR) was calculated as the ratio of family income to a poverty threshold determined by the US Bureau of the Census. 16 PIR was categorized as < 1 and 2': 1, with individuals from households with PIR< 1 considered to be living under the poverty level.

We considered the following risk factors }

Methods for GBD as potential mediators of an as-

Study population sociation between country of birth and GBD: length of overnight fast, history of

NHANES ill, a cross-sectional survey dieting, smoking status, alcohol consump­

·conducted between 1988 and 1994, followed tion, body mass index (BMI), and tradition­

a complex, four-stage probability sampling al food intake. In women, we additionally

scheme designed to represent the entire US considered number of live births, use of

civilian non-institutionalized population over birth control pills, use of oral estrogens, and the age of two months. IS Mexican Ameri­ current pregnancy status. Regular breakfast

D cans were oversampled to comprise nearly a consumption was used as a proxy for length third of the survey population. Mexican­ of overnight fast. Attempted weight loss American ethnicity was self-reported. Sur­ during the past 12 months was used as a vey participants were interviewed at home proxy for history of dieting. Subjects who in either English or Spanish and subsequent- reported smoking at least 100 cigarettes ly underwent a physical examination, a diet during their entire lifetime were classified and health interview, and various diagnostic as ever-smokers. Frequency of alcohol in­tests at a Mobile Examination Center take was estimated by summing together re­(MEC). sponses for beer, wine, and liquor from a ,:,1

III, ,!I

I

,IIi

'ii

'_h:'~.~'--------------------'--'======-";"'iij1

1­

98 Ethnicity & Disease-Vo/10, Winter 2000 -------------------- ­

,Ii­60-item food frequency questionnaire. Body mass index (BMI) was calculated us­

I ing measurements made at the MEC and categorized as <25, 25-<30, and ~30 kg/ m2, as suggested by a World Health Orga­nization Expert Committee. I?

Dietary intake was characterized in terms of patterns or combinations of foods, iden­

i tified using principal components analysisI based on responses to a 60-item food fre­II

quency questionnaire. Details of these methods are described elsewhere (Tseng M, Devellis RF, Maurer KR, et aI, in press, Public Health Nutr.) Of four patterns iden­tified in women (vegetable, high-calorie, traditional, fruit) and three in men (vege­table, high-calorie, traditional), only the tra­ditional food pattern, characterized by high intake of beans, corn tortillas, and chili pep­pers in particular, showed an association with GBD. Thus, in subsequent analyses we evaluated only the traditional food pattern as a potentially mediating variable.

Information on reproductive factors for women was obtained in a questionnaire ad­ministered at the MEC. Women were asked for the total number of live-born children they had had and if they had ever used birth control pills. Women who reported not hav­ing a menstrual period in the last two months were asked about oral estrogen or female hormone use. Women aged 20 to 59 were categorized as currently pregnant if they reported that they were or if their urine pregnancy test was positive; women aged 60 to 74 were assumed not to be pregnant.

Disease status

Participants between the ages of 20 and 74 were invited to receive a gallbladder ul­trasound examination at the MEC using real-time ultrasonography administered by a certified abdominal ultrasound technician. Prevalent cases were defined as subjects with gallstones or with no gallbladder, as indicated by ultrasound results. Gallstones were diagnosed if opacity was viewed in the gallbladder that produced a distal shad­

ow in both the supine and left decubitus views, according to commonly used crite­ria. 18 If the gallbladder was not seen in ul­trasonography and a right upper quadrant or epigastric scar was observed, it was con­cluded that a cholecystectomy, or surgical removal of the gallbladder, had been per­formed. Videotapes of all ultrasound ex­aminations were independently reviewed by • radiologists specializing in abdominal ultra­sonography. Agreement between techni­cians' and radiologists' diagnoses was eval­uated using the Kappa statistic '9 and ,was found to be 0.94.

Statistical analysis

Because GBD prevalence and risk factors differ by sex, we conducted separate anal­yses for women and men. All point esti­mates were weighted to reflect the popula­tion distribution, and variances were cal­culated using SUDAAN20 to take the com­plex sampling design into account.

Prevalence odds ratios (POR) and corre­sponding 95% confidence intervals (eI) were estimated by unconditional logistic re­gression analysis using SUDAAN. All PORs were adjusted for age by including age in the model as a continuous variable. To evaluate the possibility of interaction be­tween country of birth and either level of education or level of poverty, we examined models including these interaction terms.

We also compared age-adjusted distri­butions of potentially mediating variables between Mexico- and US-born Mexican Americans. Categorical variables were ad­justed to the 1980 US age distribution arid compared between Mexico- and US-born Mexican Americans using the Cochran­Mantel-Haenszel test statistic in SUDAAN.

To evaluate the extent to which selected risk factors for GBD mediate an association between country of birth and GBD, we in­cluded each risk factor individually in the logistic model containing country of birth and age, and then compared POR estimates for country of birth using models with and

aiiiii,.~=========

without each potential r , analyses were limited to su

with no missing informati< covariates of interest in comparability of all mode that resulted in attenuation country of birth when inch el, we stratified on levels c obtain stratum-specific POI birth.

Results

Of the 5,551 Mexican tween the ages of 20 and 7 part in NHANES III, 464 interviewed at home and il a gallbladder ultrasound. women and 2,084 men att and had usable ultrasound not born in either the Unite ico were excluded from leaving 2,082 women and L acteristics of these 4,157 shown by countryr:of birth sistent with previous resear Mexico-born Mexican Am( have completed fewer yeaJ to be poorer than Mexican in the United States. Ab( Mexican Americans born immigrated to the United, or older, and had lived in t less than half their lives, f( 12 years (data not shown).

Age-adjusted distributiol suspected GBD risk factors siderably by country of Those born in the United likely to eat breakfast ever likely to have attempted Wl

the past year. In addition, can-American men tended BMI and consumed less food pattern. US-born Me women were more like!) drink, and to use birth coni male hormone pills, were and were less likely to be

\

, , '

'Iii

'I Country of Birth and Gallbladder Disease-Tseng et al 99

Ie supine and left decubitus ng to commonly used crite­llbladder was not seen in ul­and a right upper quadrant or , was observed, it was con­cholecystectomy, or surgical e gallbladder, had been per­)tapes of all ultrasound ex­re independently reviewed by ecializing in abdominal ultra­\greement between techni­ologists' diagnoses was eval­le Kappa statistic l9 and was 94.

r:ztistical analysis

D prevalence and risk factors we conducted separate anal­en and men. All point esti­~ighted to reflect the popula­)n, and variances were cal­SUDAAN20 to take the com­design into account. )dds ratios (POR) and corre­J confidence' intervals (CI) I by unconditional logistic re­ysis using SUDAAN. All Ijusted for age by including jel as a continuous variable. ~ possibility of interaction be-of birth and either level of

:vel of poverty, we examined ng these interaction terms. lmpared age-adjusted distri­tentially mediating variables ico- and US-born Mexican Itegorical variables were ad­980 US age distribution and Neen Mexico- and US-born ~ricans using the Cochran­~el test statistic in SUDAAN. the extent to which selected GBD mediate an association

ry of birth and GBD, we in­sk factor individually in the containing country of birth

len compared POR estimates birth using models with and

without each potential mediator. These analyses were limited to survey participants with no missing information on any of the covariates of interest in order to assure comparability of all models. For variables that resulted in attenuation of the POR for country of birth when included in the mod­el, we stratified on levels of the variable to obtain stratum-specific PORs for country of birth.

Results

. Of the 5,551 Mexican Americans be­tween the ages of 20 and 74 invited to take part in NHANES III, 4641 (83.6%) were interviewed at home and invited to receive a gallbladder ultrasound. Of these, 2,090 women and 2,084 men attended the MEC and had usable ultrasound results. Subjects not born in either the United States or Mex­ico were excluded from further analysis, leaving 2,082 women and 2,075 men. Char­acteristics of these 4,157 participants are shown by country of birth in Table 1. Con­sistent with previous research, immigrant or Mexico-born Mexican Americans tended to have completed fewer years of school and to be poorer than Mexican Americans born in the United States. About 75% of the Mexican Americans born in Mexico had immigrated to the United States at age 18 or older, and had lived in the United States less than half their lives, for an average of 12 years (data not shown).

Age-adjusted distributions of known or suspected GBD risk factors also varied con­siderably by country of birth (Table 1). Those born in the United States were less likely to eat breakfast every day and more likely to have attempted weight loss during the past year. In addition, US-born Mexi­can-American men tended to have higher BMI and consumed less of a traditional food pattern. US-born Mexican-American women were more likely to smoke, to drink, and to use birth control pills and fe­male hormone pills, were of lower parity, and were less likely to be pregnant at the

time of the survey. Examination of associ­ations of these risk factors with GBD are generally consistent with previous research findings (Table 2).

Findings for GBD prevalence by country of birth are shown in Table 3. Age-adjusted prevalence of GBD was lower in Mexican Americans born in Mexico than in those born in the United States for both women and men. When Mexico-born Mexican Americans were subdivided by their length of residence in the United States, age at im­migration, and proportion of life lived in the United States, GBD prevalence in wom­en tended to be lower in those who had spent less time in the United States or who had immigrated later in life. In men, there was no apparent difference in prevalence in these subgroups, although this analysis was based on only 147 cases, 107 of whom were US-born Mexican-American men.

We included interaction terms for highest grade completed and for PIR separately and found an especially pronounced difference in prevalence among those with less edu­cation and those living below the poverty level (Table 4). In contrast, among those with more education and those living above the poverty level, differences in prevalence were considerably diminished. In men with more education, the association even ap­peared to be reversed, although confidence intervals for those born in Mexico were wide. In general, US-born Mexican Amer­icans with less education or who were liv­ing below the poverty level had signifi­cantly higher prevalence of GBD compared to all other groups.

To evaluate the extent to which the dif­ference in GBD prevalence by country of birth might be mediated by selected risk factors for GBD, each risk factor was added singly to the model containing only age and country of birth (Table 5). To assure com­parability across models, results are pre­sented for 1,990 women and 2,064 men with no missing information for any risk factors. Among women, adding history of

I,

I ':1 I

II

II'11

IIil

IIII Ii I

I i

;1\

il i

]

I

."II 100 Ethnicity & Disease-Vol 10, Winter 2000 --------------------- ­

I' Table 1.-Mean age and age-adjusted distributions' of socioeconomic characteristics and selected GBD risk factors by country of birth and sex in Mexican Americans: NHANES III, 1988-94

'l' Women Men

US Mexico US Mexico (N = 1079)t (N = 1003) (N = 945) (N = 1130)

Mean age (yrs) 38.9 35.8 39.3 33.7 Highest grade completed <12 40.5 79.2:1: 39.5 79.5:1: Poverty-income ratio < I 26.9 48.9:1: 23.0 39.2:1:

II 8MI I <25 33.1 30.6 29.2 35.2I

25-<30 30.3 36.0 43.0 46.1 "'=30 36.6 33.4:1: 27.8 18.7:1:

Tried to lose weight last year 56.9 35.4:1: 34.8 20.3:1: Eat breakfast every day 41.2 71.6:1: 43.8 66.8:1: Ever smoked> 100 cigarettes 36.2 22.7:1: 59.8 61.6

Alcohol consumption last month

Never 55.3 79.0 32.4 36.0 <I/week 18.0 9.5 13.2 12.9 1-2/week 17.4 7.2 22.6 24.7 >2/week 9.4 4.4:1: 31.8 26.4:1:

I . I Traditional food pattern score quartile

I 40.6 11.2 48.9 10.9 2 33.3 19.6 27.9 20.0 3 16.7 32.1 15.0 33.4 4 9.4 37.1 :I: 8.2 35.7:1:

Number of live births

0 16.5 12.3 1-2 35.5 30.2 3-4 30.1 28.8 >4 17.8 28.7:1:

Ever used birth control pills 64.6 44.5:1: Ever used estrogens or female hormones 13.8 5.9:1: Currently pregnant 4.3 6.9

* Proportions at levels of all covariates were adjusted to the 1980 US age distribution and weighted to reflect population distribution.

tN's may differ for each covariate due to missing data. :I: P value<.O I for Cochran-Mantel-Haenszel test statistic comparing US- and Mexico-born.

dieting slightly attenuated the POR for food intake. Among men in the upper t~o country-of-birth, but not when BMI was quartiles, however, the POR for Mexico- Vs also included in the model. Among men, US-born Mexican-American men was 0.32 addition of variables representing level of (95% CI 0.14,0.74). In other words, in men traditional food pattern intake resulted in at­ with similarly high intake of a traditional tenuation of the POR from 0.63 to 0.80, food pattern, those born in Mexico still had suggesting that dietary differences contrib­ a substantially lower prevalence of GBD uted to the difference in prevalence. Using than those born. in the United States. stratified analysis, there was little associa­ Among women and men with less edu­tion between country of birth and GBD cation who were living below the poverty (POR = 1.30, 95% CI 0.68, 2.48) among level, Mexico-born Mexican Americans men in the lower two quartiles of traditional continued to be considerably less likely to

Table 2.-Age-adjusted prevalent of covariates in Mexican Americal

8MI (kg/m2)

<25 25-<30 "'=30

Ever smoked> 100 cigarette* Eat breakfast every day* Tried to lose weight last year*

Frequency of alcohol consumptiol

Never <lIweek 1-2/week >2/week

Quartile of traditional food patten

1 2 3 4

Number of live births

o 1-2 3-4 >4

Currently pregnant* Ever used birth contr~1 pills* Ever used estrogens or female ho

* POR for yes vs 'no.

have GBD than those bor States after controlling for mediating risk factor, inch food intake (results not she

Discussior

Using data from NHANl a lower prevalence of GJ Americans born in Mexic born in the United States. was more pronounced a Americans with less educal ing below the poverty leve ican Americans with less e( living below the poverty Ie have an especially high pre Although there were subst~

in the distribution of risk by country of birth, no si

. 1\

---------------- Country of Birth and Gallbladder Disease-Tseng et al 101

Table 2.-Age-adjusted prevalence odds ratios and 95% confidence intervals for gallbladder disease by levels of covariates in Mexican Americans, by sex: NHANES III, 1988-94

haracteristics and selected GBD risk 188-94

Men Women Men

co US Mexico BMI (kg/m2) 003) (N = 945) (N = 1130)

<25 1.00 1.00 l 39.3 33.7 25-<30 1.34 (0.89. 2.03) 0.80 (0.42, 1.52) 1:1: 39.5 79.5:1: ;",30 2.83 (2.10. 3.80) 1.12 (0.69, 1.84) l:l: 23.0 39.2:1: Ever smoked> 100 cigarette* 1.24 (0.84. 1.85) 0.74 (0.42, 1.33)

Eat breakfast every day* 0.83 (0.64. 1.07) 1.23 (0.85, 1.79) Tried to lose weight last year* 1.58 (1.14, 2.17) 0.84 (0.46, 1.55)

29.2 35.2 ) 43.0 46.1 Frequency of alcohol consumption last month

1:1: 27.8 18.7:1: 'Never 1.00 1.00 1:1: 34.8 20.3:1: . <l/week 1.00 (0.60, 1.65) 1.32 (0.58, 2.99) 5:1: 43.8 66.8:1: 1-2/week 0.78 (0.42, 1.45) 0.71 (0.43, 1.18) 7:1: 59.8 61.6 >2/week 0.52 (0.29, 0.91) 0.63 (0.37, 1.08)

Quartile of traditional food pattern intake

32.4 36.0 I 1.00 1.00 13.2 12.9 2 1.16 (0.86, 1.57) 0.74 (0.41, 1.35) 22.6 24.7 3 1.02 (0.75, 1.39) 0.40 (0.20, 0.81)

1:1: 31.8 26.4:1: 4 0.83 (0.59, 1.17) 0.54 (0.29, 1.02) ,,.Number of live births

48.9 10.9 o 1.00 "I 27.9 20.0 1-2 2.73 (1.43, 5.22)

I 15.0 33.4 3-4 3.39 (1.77, 6.49) f 1:1: 8.2 35.7:1: >4 2.91 (1.53, 5.55)

Currently pregnant* 0.56 (0.27, 1.14) 1 Ever used birth control pills* 1.29 (0.93, 1.80) I Ever used estrogens or female hormones* ) 1.04 (0.49, 2.17)

~ * POR for yes vs no. 7:1: i:l: 1:1: have GBD than those born in the United stood out as a primary mediator of the as­I States after controlling for each potentially sociation between country-of-birth and :e distribution and weighted to reflect mediating risk factor, including traditional GBD prevalence.

food intake (results not shown). Prevalence of GBD may vary by country of birth due to differences in health-related

- and Mexico-born. Discussion attitudes and behaviors, including health Using data from NHANES III, ~e found knowledge,21 cigarette smoking,22 eating at­

\mong men in the upper two a lower prevalence of GBD in Mexican titudes,23 dietary intake,8.24.25 and alcohol 'ever, the POR for Mexico- vs Americans born in Mexico than in those use.26-28 In our analyses, we also found sub­ican-American men was 0.32 D born in the United States. The difference stantial differences in the distributions of ,0.74). IIi other words, in men was more pronounced among Mexican several risk factors for GBD, including obe­I high intake of a traditional Americans with less education or those liv­ sity, diet, parity, and use of birth control those born in Mexico still had ing below the poverty level. US-born Mex­ pills. However, the prevalence difference y lower prevalence of GBD ican Americans with less education or those persisted when we controlled for these po­rn in the United States.. living below the poverty level appeared to tentially mediating factors, both individu­men and men with less edu­ have an especially high prevalence of GBD. ally and as a group. 'ere living below the poverty Although there were substantial differences Possibly, adjusting for some potential o-born Mexican Americans in the distribution of risk factors for GBD mediators did not change estimated mea­be considerably less likely to by country of birth, no single risk factor sures of association between country of

d"1.0'­~ '::-~

1

1

102 Ethnicity & Disease-Vo/10, Winter 2000 ---------------------­

Table 3.-Age-adjusted* prevalences and prevalence odds ratios (PORs) for gallbladder disease (GBD) by country of birth in Mexican Americans, by sex: NHANES III, 1988-94

Women Men

Prev- Prev-N alenee PORt N alence PORt

I

US-born 1079 29.1 1.00 945 9.8 1.00 Mexico-born

All 1003 23.7 0.70 (0.50, 0.98) 1130 6.7 0.63 (0.40, 0.97)

Length of residence

2: 10 yrs 503 24.0 0.70 (0.50, 0.97) 562 5.4 0.50 (0.28, 0.90) I <10 yrs 373 19.2 0.64 (0.33, 1.23) 435 1.8 0.60 (0.27, 1.33)

Age at immigration

<18 yrs 220 26.0 0.81 (0.51, 1.31) 282 3.6 0.48 (0.16, 1.42) 2: 18 yrs 656 22.2 0.64 (0.42, 0.97) 715 5.6 0.53 (0.31, 0.93)

Proportion of life lived in US

2:50% 208 29.6 1.10 (0.77, 1.57) 231 5.4 0.53 (0.24, 1.16) <50% 668 20.2 0.55 (0.35, 0.87) 766 4.9 0.52 (0.29, 0.93)

* Prevalences were age-adjusted to the 1980 US age distribution. Prevalence odds ratios were age-adjusted by including age as a continuous variable in logistic regression analysis.

t US-born Mexican Americans are referent group for all prevalence odds ratios.

Table 4.-Age-adjusted* prevalences and prevalence odds ratios (PORs) for gallbladder disease (GBD) by country of birth stratified on highest grade completed and poverty-income ratio in Mexican Americans, by sex: NHANES III, 1988-94

Women Men

US Mexico US Mexico

(N = 1075) (N = 996) (N = 939) (N = 1115)

Highest grade completed

0-11

paR (95% CI) 1.00 0.55 (0.38, 0.81) 1.00 0.40 (0.25, 0.65) Prevalence 34.6 24.2 12.3 6.0

2: 12

paR (95% CI) 0.65 (0.47, 0.89) 0.54 (0.27, 1.08)t 0.62 (0.35, I. I l) 1.02 (0.45, 2.34)t Prevalence 24.5 18.0 9.0 12.7

(N = 982) (N = 856) (N = 863) (N = 956)

Poverty-income ratio

0-<1

paR (95% CI) 1.00 0.57 (0.31, 1.05) 1.00 0.33 (0.13, 0.84) Prevalence 36.3 24.2 13.6 6.2

2:1

paR (95% CI) 0.65 (0.43, 0.96) 0.49 (0.31, 0.77) 0.68 (0.36, 1.32) 0.53 (0.23, 1.22)t Prevalence 26.6 22.5 9.4 6.9

* Prevalences were age-adjusted to the 1980 US age distribution. Prevalence odds ratios were age-adjusted by

I including age as a continuous variable in logistic regression analysis.

t P for interaction <.10.

~I

1

Table 5.-Prevalence odds ratio ales, by sex: NHANES III, 1988­

Adjusted for:

Age Age, BMI Age, tried to lose' weight last yea] Age, BMI, tried to lose weight la Age, breakfast every day Age, ever smoked Age, alcohol consumption Age, traditional food intake patter Age, number of live births Age, ever used birth control pills Age, ever used estrogen Age, currently pregnant Age, all other covariates

birth and GBD because thl cient validity. For example, have been more completel: adjusting for smoking dose vs never having smoked, all coded as 4 categories\ (m rent< 1ppd, current> = 1 PI sociated with GBD in men a associated with GBD in w 1.10; 95% CI 1.00-1.21; P dition, more specific measu tors, such as amount and ral loss, rather than attempted 1

year, may have yielded stl tions. The fact that even as c as attempted weight loss la: sociated with GBD in wome

• weight loss may be more mediator than could be ref analyses.

POR estimates may also partially adjusted since in available on recent rather "exposure" for factors sud dietary and alcohol intake these factors over time rna misclassification of individm to these potential mediators, level of "exposure" may h recent immigrants as a resul or in some GBD cases as a n

, .

IS) for gallbladder disease (GBD) by

Men

Prev­alence PORt

5 9.8 1.00

o 6.7 0.63 (0040, 0.97)

2 SA 0.50 (0.28, 0.90) 5 1.8 0.60 (0.27, 1.33)

2 3.6 0048 (0.16, 1042) 5 5.6 0.53 (0.31, 0.93)

I SA 0.53 (0.24, 1.16) 6 4.9 0.52 (0.29, 0.93)

~nce odds ratios were age-adjusted by

Is ratios.

s) for gallbladder disease (GBD) by i ratio in Mexican Americans, by sex:

Men'

us Mexico

N = 939) (N = 1115)

1.00 0040 (0.25, 0.65) 12.3 6.0

~ (0.35, 1.11) 1.02 (0045, 2.34)t 9.0 12.7

N = 863) (N = 956) D

1.00 0.33 (0.13,0.84) 13.6 6.2

~ (0:36, 1.32) 0.53 (0.23, I :22)t 904 6.9

:nce odds ratios were age-adjusted by

---------------- Country of Birth and Gallbladder Disease-Tseng et al 103

Table 5.-Prevalence odds ratio for Mexico- vs US-born Mexican Americans adjusted for age and other covari­ates, by sex: NHANES III, 1988-94

Women Men Adjusted for: (N = 1990) (N = 2064)

Age 0.74 (0.5 I, 1.06) 0.63 (0040, 0.97) Age,8MI 0.73 (0.50, 1.07) 0.64 (0041, 0.98) Age, tried to lose weight last year 0.80 (0.56, 1.14) 0.61 (0.39, 0.94) Age, 8MI, tried to lose weight last year 0.78 (0.54, 1.13) 0.62 (0040, 0.95) Age, breakfast every day 0.76 (0.53, 1.10) 0.59 (0.36, 0.96) Age, ever smoked 0.76 (0.55, 1.06) 0.63 (0040, 0.97) Age, alcohol consumption 0.68 (0048, 0.97) 0.62 (0.39, 0.98) Age, traditional food intake pattern 0.75 (0.53, 1.07) 0.80 (0042, 1.54) Age, number of live births 0.71 (0049, 1.0 I) Age, ever used birth control pills 0.77 (0.54, I. J0) Age, ever used estrogen 0.74 (0.49, 1.09) Age, currently pregnant 0.75 (0.52, 1.08) Age, all other covariates 0.75 (0.53, 1.07) 0.73 (0.38, 1041)

birth and GBD because they lacked suffi­ symptoms or diagnosis. When we excluded cient validity. For example, smoking rn!ght from our analyses two groups of individuals have been more completely controlled by who may have experienced shifts in expo­adjusting for smoking dose rather than ever sure that could have biased results-name­vs never having smoked, although smoking ly, recent immigrants and cases who had coded as 4 categories (never, past, cur­ undergone cholecystectomy or who had rent< 1ppd, current> = 1 ppd) was not as­ been told that they had gallstones-findings sociated with GBD in men and only weakly were similar (results not shown). Neverthe­associated with GBD in women (paR = less, our findings for recent consumption of 1.10; 95% CI 1.00-1.21; P = .02).3 In ad­ the traditional food pattern in men suggest dition, more specific measures of risk fac­ that diet measured for a more appropriate tors, such as amount and rapidity of weight period of time may be worth investigating loss, rather than attempted weight loss last further as an explanatory factor. year, may have yielded stronger associa­ The association between country of birth tions. The fact that even as crude a measure and GBD may be due to other risk factors as attempted weight loss last year was as­ not considered in our analyses, such as sociated with GBD in women suggests that physical activity,29-31 or aspects of the diet

• weight loss may be more important as a not captured by our measure of food pattern medi(:itor than could be reflected in these intake, such as amount or method of prep­analyses. aration. It is also possible that there were

paR estimates may also have been only combinations of factors or aspects of a spe­partially adjusted since information was cific lifestyle that we could not capture us­available on recent rather than long-term ing measures of individual risk factors. The "exposure" for factors such as BMI, and group of less-educated Mexico-born men dietary and alcohol intake. Variation in with a high level of intake of the traditional these factors over time may have led to food pattern, for example, may represent a misclassification of individuals with respect select group of people with some combi­ jl

I Ito these potential mediators. For example, nation of factors that protect against GBD.

level of "exposure" may have shifted in Other differences between Mexico- and I recent immigrants as a result of migration, US-born Mexican Americans may also con­or in some GBD cases as a result of disease tribute to the observed difference in prev- I,

'~Hj_lIit::jJ~. _ __

I

J

I

104 Ethnicity & Disease-Vol 10, Winter 2000 --------------------- ­

alence, such as their place of· residence in individual risk factors for GBD appeared the United States, the social, political, and sufficient to explain this disparity. Thus, the economic circumstances under which they difference in prevalence of GBD remains or their ancestors migrated, and the oppor­ largely unexplained, even by the strongest tunities available to them upon their arriv­ . known risk factors for the disease. Possible al-although these are differences that are explanations for the prevalence difference difficult to capture in these survey data. A require evaluation in future research. Our better understanding of these differences currently limited understanding of the dis­may form the basis for intervention to pre­ tribution of GBD in the Mexican-American vent disease in US-born Mexican Ameri­ population points to the need to explore cans. whether-and how-the burden of GBD

Factors associated with the migration morbidity can be lessened in a subpopula­process may influence rates of disease in tion at particularly high risk for this disease. immigrant groups. For example, lower GBD prevalence in Mexico-born Mexican Acknowledgements Americans may be evidence of a "healthy This research was supported in part by grants T32 migrant" effect, although such a selection DK07634 and P30 DK34987 from the National Insti ­hypothesis is difficult to evaluate empiri ­ tutes of Health.

cally.32 Lower GBD prevalence may also reflect the continued influence of health-de­ References terminants related to living in Mexico, in­ I. Everhart JE. Gallstones. In: Everhart J, ed .. Diges­cluding health-related influences that oc­ tive Diseases in the United States: Epidemiology curred prenatally or during childhood.33.34 and Impact. Washington, DC: US Government

Mechanisms by which health status earlier Printing Office; 1994:647-690. 2. Sampliner RE, Bennett PH, Comess LJ, Rpse RA,in life could influence development of GBD

Burch TA. Gallbladder disease in Pima Indians:later have yet to be explored. demonstration of high prevalence and e~ly onset

Given the reasonably high participation by cholecystography. N Engl J Med. 1970;283: rate, it is unlikely that the observed differ­ 1358-1364.

ence in prevalence by country of birth is a 3. Everhart J, Khare M, Hill M, Maurer KR. Preva­lence and ethnic differences in gallbladder diseaseresult of selection bias. Severe overestima­in the United States. Gastroenterology. In press.

tion of GBD prevalence in US-born Mexi­ 4. Diehl AK. Epidemiology and natural hi'story of

I I can Americans, or underestimation in Mex­ gallstone disease. Gastroenterol Clin North Am. 'I ico-born Mexican Americans, is also un­ 1991;20: 1-19.H :1 likely. Although it is possible that not all 5. Weiss KM, Ferrell RE, Hanis CL A new world

syndrome of metabolic diseases with a genetic andcholecystectomy cases in our study popu­" evolutionary basis. Yearbook Phys Anihropol.lation had gallstones, there is little reason 1984;27:153-178. i to expect differences in indications for cho­ 6. Hanis CL, Chakraborty R, Ferrell RE, Schull WJ. lecystectomy by country-of-birth. Individual admixture estimates: disease'

I associa-

In summary, we found a higher preva­ tions and individual risk of diabetes and gallblad­der disease among Mexican Americans in Starrlence of GBD in US- than in Mexico-born County, Texas, Am J Phys Anthropol. 1986;70:

Mexican Americans. Our research adds to

I433-441.

a substantial literature suggesting poorer 7. Skerry P. Mexican Americans: The Ambivalent health status in Mexican Americans born in Minority. Cambridge, Mass: Harvard University

1,1 the United States relative to immigrant Press; 1993. 8, Guendelman S, Abrams B. Dietary intake among

: ~ Mexican Americans. 35 In our analyses, the Mexican-American women: generational differ­

! ~ difference in GBD prevalence was espe­ences and a comparison with white non-Hispanic

cially pronounced among individuals of women. Am J Public Health. 1995;85:20-25. low socioeconomic status, and none of the 9. Gilbert MJ, Alcohol-consumption patterns in im­

migrant and later generati women, Hisp J Behav Sci.

10. Cervantes RC, Gilbert MJ, AM. Psychosocial and COB

cohol use in younger adu born Hispanics, lnt J Addie

I L Scribner R, Dwyer JH. j

birth weight among Latino NES. Am J Public Health.

12, Collins JW Jr, Shay OK. F weight among· Hispanic States-born and foreign-bor urban poverty. Am J Epic. 192.

13. Sorlie PO, Backlund E, J Mortality by Hispanic statu JAMA. 1993;270:2464-246

14. Wei M, Valdez RA, Mitd Stern MP, Hazuda HP. Mig] nomic status, and mortal Americans and non-Hispan tonio Heart Study. Ann EJ 313.

15. US Department of Health (DHHS), National Center Plan and Operation of the and Nutrition Examinatihn attsville, Md: Centers for Di vention; 1994, Vital and H 1(32).

16. US Department of Health (DHHS), National Center Third National Health and. Survey. 1988-1994, NHANl Data File (CD-ROM). Hy; for Disease Control and Pn Use Data File Documentati(

17. WHO Expert Committee. P and interpretation of anthro WHO Expert Committee. Tech Rep Ser. 1995;854: 1:-'

18. US Department of Health (DHHS), National Center Third National Health and Survey, 1988-/994, NHAJ Data File (CD-ROM). Hy~

for Disease Control and Pre Use Data File Documentatic

19. Fleiss JL Statistical MethOl portions. New York, NY: Inc; 1981.

20. Shah BV, Barnwell BG, User's Manual, Release 7. Park, NC: Research Triangle

1

H

Country of Birth and Gallbladder Disease-Tseng et al 105

factors for GBD appeared llain this disparity. Thus, the revalence of GBD remains ined, even by the strongest ors for the disease. Possible r the' prevalence difference Ion in future research. Our

il! d understanding of the dis­D in the Mexican-American Its to the need to explore how-the burden of GBD )e lessened in a subpopula­rly high risk for this disease.

nowledgements

IS supported in part by grants T32 DK34987 from the National Insti-

References

lllstones. In: Everhart J, ed. Diges­7 the United States: Epidemiology vashington, DC: US Government

1994:647-690. Bennett PH, Comess LJ, Rose RA, Ibladder disease in Pima Indians: )f high prevalence and early onset raphy. N Engl J Med. 1970;283:

lfe M, Hill M, Maurer KR. Preva­~ differences in gallbladder disease tates. Gastroenterology. In press. demiology and natural history of se. Gastroenterol Clin North Am.

Tell RE, Hanis CL. A new world ~tabolic diseases with a genetic and ,asis. Yearbook Phys Anthropol. 78.� kraborty R, Ferrell RE, Schull WJ.� jxture estimates: disease associa­�dual risk of diabetes and gallblad­�ong Mexican ,hmericans in Starr� Am� J phys Anthropol. 1986;70:

ican Americans: The Ambivalent xidge, Mass: Harvard University

Abrams B. Dietary intake among can women: generational differ­mparison with white non-Hispanic 'ublic Health. 1995;85:20-25. ;ohol-consumption patterns in im­

migrant and later generation Mexican-American women. Hisp J Behav Sci. 1987;9:299-313.

10.� Cervantes RC, Gilbert MJ, de Snyder NS, Padilla AM. Psychosocial and cognitive correlates of al­cohol use in younger adult immigrant and US­born Hispanics. Int J Addict. 1991;25:687-708.

I I. Scribner R, Dwyer JH. Acculturation and low birth weight among Latinos in the Hispanic HA­NES. Am J Public Health. 1989;79: 1263-1267.

12.� Collins JW Jr, Shay OK. Prevalence of low birth weight among Hispanic infants with United States-born and foreign-born mothers: the effect of

I urban poverty. Am J Epidemiol. 1994;139: 184­192.

(3.� Sorlie PO, Backlund E, Johnson NJ, Rogot E. Mortality by Hispanic status in the United States. JAMA. 1993;270:2464-2468.

14.� Wei M, Valdez RA, Mitchell BD, Haffner SM, Stern Mp, Hazuda HP Migration status, socioeco­nomic status, and mortality rates in Mexican Americans and non-Hispanic whites: the San An­tonio Heart Study. Ann Epidemiol. 1996;6:307­313.

15.� US Department of Health and Human Services (DHHS), National Center for Health Statistics. Plan and Operation of the Third National Health and Nutrition Examination Survey, 1988-94. Hy­attsville, Md: Centers for Disease Control and Pre­vention; 1994. Vital and Health Statistics, Series 1(32).

16.� US Department of Health and Human Services (DHHS), National Center for Health Statistics. Third National Health and Nutrition Examination Sun1ey, /988-/994. NHANES II/ Household Adult Data File (CD-ROM). Hyattsville, Md: Centers for Disease Control and Prevention; 1996. Public Use Data File Documentation No. 77560.

17.� WHO Expert Committee. Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. World Health Organ) Tech Rep Ser. 1995;854: 1-452.

18.� US Department of Health and Human Services (DHHS), National Center for Health Statistics. Third National Health and Nutrition Examination Survey. /988-/994. NHANES III Examination Data File (CD-ROM). Hyattsville, Md: Centers for Disease Control and Prevention; 1996. Public Use Data File Documentation No. 76200.

19.� Fleiss JL. Statistical Methods for Rates and Pro­portions. New York, NY: John Wiley and Sons Inc; 1981.

20.� Shah BV, Barnwell BG, Bieler GS. SUDAAN User's Manual, Release 7.0. Research Triangle Park, NC: Research Triangle Institute; 1996.

21.� Vega WA, Sallis JF, Patterson T, Rupp J, Atkins C, Nader PRo Assessing knowledge of cardiovas­cular health-related diet and exercise behaviors in Anglo- and Mexican-Americans. Prev Med. 1987; 16:696-709.

22.� Otero-Sabogal R, Sabogal F, Perez-Stable EJ, Hiatt RA. Dietary practices, alcohol consumption, and smoking behavior: ethnic, sex, and acculturation differences. J Natl Cancer Inst Monogr. 1995;18: 73-82.

23.� Pumariega AJ. Acculturation and eating attitudes in adolescent girls: a comparative and correlation­al study. J Am Acad Child Psychiatry. 1986;25: 276-279.

24.� Elder JP, Castro FG, de Moor C, et al. Differences in cancer-risk-related behaviors in Latino and An­glo adults. Prev Med. 1991 ;20:751-763.

25.� Winkleby MA, Albright CL, Howard-Pitney B, Lin J, Fortmann SP Hispanic/white differences in dietary fat intake among low educated adults and children. Prev Med. 1994;23:465-473.

26.� Black SA, Markides KS. Acculturation and alco­hol consumption in Puerto Rican, Cuban-Ameri­can, and Mexican-American women in the United States. Am J Public Health, 1993;83:890-893.

27.� Caetano R, Mora ME. Acculturation and drinking among people of Mexican descent in Mexico and the United States. J Stud Alcohol. 1988;49:62-71.

28.� Markides KS, Krause N, Mendes de Leon CF. Ac­culturation and alcohol consumption among Mex­ican Americans: a three-generation study. Am J Public Health. 1988;78: 1178-1181.

29.� J0rgensen T. Gallstones in a Danish population. Relation to weight, physical activity, smoking, coffee consumption, and diabetes mellitus. Gut. 1989;30:528-534.

30.� Kato I, Nomura A, Stemmermann GN, Chyou PH. Prospective study of clinical gallbladder disease and its association with obesity, physical activity, and other factors. Dig Dis Sci. 1992;37:784-790.

31.� Leitzmann MF, Giovannucci E, Rimm EB, Stamp­fer MJ, Willett We. Physical activity and the risk of gallstone disease in men. Ann Intern Med. 1998; 128:415-425.

32.� Smaje C. The ethnic patterning of health: new di­rections for theory and research. Sociol Health Ill­ness. 1996; 18: 139-171.

33.� Macintyre S. The Black Report and beyond: what are the issues? Soc Sci Med. 1997;44:723-745.

34.� Wadsworth MEJ. Health inequalities in the life course perspective. Soc Sci Med. 1997;44:859­869.

35.� Vega WA, Amaro H. Latino outlook: good health, uncertain prognosis. Annu Rev Public Health, 1994; 15:39-67.

1� I

,'I!' Ii iii '~ Ii

l

I I� I� I I

'­