A validated, disease-specific quality of life measure for acoustic

neuromaBrian Shaffer, M.D.February 26, 2009

Faculty discussant: Michael Ruckenstein, MD

Otorhinolaryngology: Head and Neck Surgery at PENN Excellence in Patient Care, Education and Research since 1870

Acoustic neuroma

• Acoustic neuromas are the most common temporal bone neoplasms– CPA acoustic neuromas represent 10% of

all intracranial tumors

• Mortality rates are far less than 1%, but there is often considerable associated morbidity from the tumor itself or as a consequence of its treatment

Acoustic neuroma

• Majority of patients aged 40-54– For many this represents a period of

maximum family, social and occupational responsibility

– Potential for significant disruption is large

• Many studies focus on physical disability, but few examine psychosocial or economic impact

QOL with acoustic neuroma

• 1977: Medline adds “quality of life” as a keyword/MeSH heading

• 1986, Lohne V et al: “I want to smile. How do individuals with facial paralysis resulting from surgical removal of an acoustic neuroma cope with daily living?”15

QOL with acoustic neuroma

• Laryngoscope 1989: Wiegand and Fickel find a considerable discrepancy between the assessment of postoperative facial nerve function as judged by patients and their surgeons35

– Surgeons generally underrated the functional disability

– What followed was a large number of publications focusing on post-operative quality of life issues

– Many continued to focus just on symptom reporting without QOL measures1,9,10,22,25,28,30,32,34

QOL with acoustic neuroma

• Laryngoscope 1998, Nikolopoulos TP et al: investigate quality of life 1-3y after microsurgery21

Generic vs. disease-specific scales

• Generic scales useful for making comparisons between different diseases and conditions

• Disease-specific scales useful when disease or condition-related attributes need to be assessed, and when greater sensitivity to the clinical condition under consideration is required4

– Facial nerve function/appearance, hearing, balance, etc.

• Often recommended to use both types of scales side-by-side in order to address both clinical and broader policy questions18

QOL with acoustic neuroma

• Many studies have embraced the SF-36 generic health-related QOL scale with varied results

• Recognizing the limitations of a generic scale, authors have also designed and employed multiple different scales– Authors frequently use their own

questionnaires– None of these instruments has been validated

for acoustic neuroma patients

Assessing validity

• Validity is the degree to which a scale measures what it is intended to measure

• This is challenging with QOL studies because the measurement of QOL factors depends on their definitions– These will typically vary from researcher to

researcher and patient to patient

Validated QOL measures

• Why use validated scales?• Example from psychiatric literature

– Marshall (2000) reviewed 300 randomized controlled trials of schizophrenia17

– Studies were 40% more likely to report that treatment was effective when they used unpublished scales rather than validated ones

– 1/3 of claims of treatment superiority would not have been made if the studies had used published scales

Assessing validity

• Face validity: unambiguous and appropriate, appears to measure what is intended

• Content validity: all relevant concepts covered• Criterion validity: correlation with gold standard

– No gold standard exists for acoustic neuroma!

• Construct validity: hypothesis testing– Convergent validity: correlation with related indicators– Divergent validity: uncorrelated with unrelated

indicators– Discriminative validity: discriminates different patient

groups• Not as relevant in our study as not a screening tool

– Exploratory factor analysis: confirm a subscale structure

Methods

• Our goal is to develop and validate a new disease-specific QOL measure for patients with a diagnosis of acoustic neuroma– Literature review and scale development– Application to patient cohort and chart

review– Statistical analysis for validity testing and

item reduction– Reliability testing

Devising items

• Critical literature review– Compendia of QOL scales– Focus on studies presenting open-ended

questionnaires2,13,20,24,28

• Face and content validity assessed by internal and external expert review– Face validity: low ready level, consistency in

wording (positively worded), items of short length– Content validity: all relevant domains appear

covered from an otology and psychosocial perspective, and all domains from open-ended questionnaires addressed

Devising items

• Bateman N et al (2000) compiled 279 responses from 53 questionnaires, and presented responses using patients’ actual wording2

Devising items• Survey results from the Acoustic Neuroma

Association (Ryzenman 2004) asked patients to identify the “most difficult aspect” of their acoustic neuroma experience28

Preliminary survey

• The preliminary survey was an 88 question self-administered survey– 80 bipolar Likert items (strongly disagree, disagree,

neutral, agree, strongly agree)– 8 visual analogue scale (VAS) items meant to assess

global quality of life in various domains– Included a modification of the Hospital Anxiety and

Depression Scale (HADS), a reliable and valid screen for anxiety and depression36

• Domains covered included hearing, balance, facial/eye symptoms, activities of daily living, pain, anxiety/depression, energy/vitality, general health

Data collection• IRB approval obtained• 262 patients contacted via mail with packet that

included:– Introductory letter– Informed Consent and HIPAA consent request– Preliminary survey copy– SF-36 copy

• 117 returned, complete surveys with proper consents– Complete response rate of 45%

• Chart review completed, recording:– Demographics, audiogram results, tumor size,

treatment plan, House-Brackmann facial nerve score, years since diagnosis, and years since treatment.

Data collection

Cases (N=117)Age, years 60.4 Range 20-84Gender, N (%) Male 55 (47) Female 62 (53)Years since diagnosis 5.5Treatment, N (%) Conservative 59 (50) Surgery 48 (41) Gamma Knife 10 (9)Years since treatment 5.1Tumor size, mm 16 Range 2-60House-Brackmann score, N (%) I 74 (81) II 5 (6) III 8 (9) IV 2 (2) V 2 (2) VI 0 (0)Pure-Tone Average, dB 57Speech Recognition Threshold, dB 55Speech Discrimination Score, % 41

Patient Demographics and Disease Characteristics

Psychometric analysis

• Start with a broad initial survey with built-in redundancy, then apply stepwise item reduction strategies– 1. Eliminate items with high floor/ceiling effects– 2. Eliminate items with low item-total

correlation– 3. Eliminate items with high item-item

correlation– 4. Exploratory factor analysis, eliminating items

with ambiguous subscale structure

Frequency of Endorsement

• Items with very low/high endorsement (i.e. floor/ceiling effects) are not sufficiently informative and do not respond well to change– Items with a floor or ceiling effect of >0.7

were eliminated6,8 – Resulted in elimination of 5 items

Item-Total Correlation

• Measure of internal consistency• Examine correlation of each individual

item score with the scale total– Items with Item-Total correlations < 0.4

discarded11,31

– Resulted in elimination of 18 items

Item-Item correlation

• Very high correlations between different items suggests redundancy

• For item pairs with item-item correlations > 0.7, the item with the lowest item-total correlation was eliminated8,11

– Each pair was inspected to ensure that the items did appear to be measuring similar attributes

– Resulted in elimination of 18 items• 42 items remained at this stage

Exploratory factor analysis

• Significance tests play a far less important role in multivariate analysis than in univariate analysis– With measurement scales, each item

becomes a unique variable, giving 42 variables in our system!

• The main emphasis is put on finding natural groupings of questions– Exploratory factor analysis is a powerful

method of demonstrating these groupings

Exploratory factor analysis

• Factor analysis seeks to combine variables (i.e. questions) into a smaller number of “principal components” – or groups – that are still informative– Explores the dimensionality of the scale

• This then allows one to identify an underlying structure to the data (i.e. subscales)

– Individual items will typically fall within one of the different subscales

Exploratory factor analysis

• Confirms that items and/or groups of items are measuring what they were intended to measure– Items that group with more than one subscale or that

group with the “wrong” subscale are ambiguous and should be eliminated12,31

• Our analysis identified a natural 7-factor/group solution and eliminated 14 ambiguous items– Leaving a final 28-item survey– That these purely statistical groupings make sense to

the knowledgeable reader supports the validity of the scale

Item Item Description 1 2 3 4 5 6 754 Get frightened feeling 0.7556 Worrying thoughts 0.5560 "Butterflies" in the stomach 0.7564 Sudden feelings of panic 0.7070 Difficulty falling/staying asleep 0.4526 Problems moving face 0.8627 Eye discomfort/tearing 0.6029 Speech affected by face 0.7766 Decreased sexual drive -0.5676 Health is excellent -0.6578 Expect health to get worse -0.6911 Dizziness -0.6312 Unsteady -0.8313 Whirling/falling when walking -0.6815 Difficulty changing directions -0.7718 Trouble walking in dark -0.5821 Afraid of appearing intoxicated -0.603 Hearing loss 0.736 Difficulty in conversations 0.71

10 Tinnitus 0.5267 Isolation 0.6147 Accomplish less -0.5459 Feel slowed down -0.5971 Difficulty concentrating -0.6172 Impatient -0.6974 Lacking energy -0.6475 Memory -0.7448 Head pain 0.76

Cronbach's alpha value 0.78 0.69 0.65 0.86 0.77 0.88 NARotation method: Varimax with Kaiser normalization.For clarity only the factor loadings of greatest magnitude are shown.NA = not applicable with only one item

ComponentExploratory Factor Analysis for 28 Remaining Items

Scoring

• Item scores transformed and calculated on a scale of 0 to 100 (worst to best QOL)

• Domain/group scores similarly calculated as average of component item scores

• Total score an equal average of individual domain/group scores– An overall weighted total to reflect difference in

number of items in different domains

Scale and Domain Distributions

Scale and Domain Distributions

Mean MedianStandard Deviation Skewness % Floor % Ceiling

Hearing 65.4 68.9 22.4 -0.30 0 8

Balance 72.3 75.0 20.0 -0.40 0 13

Face/Eye 83.9 91.7 20.2 -1.40 1 46

Anxiety 72.7 75.0 20.0 -0.60 0 11

Energy 68.4 67.5 22.7 -0.30 0 14

Pain 76.5 75.0 28.5 -1.10 3 47

General 64.4 66.7 20.1 -0.20 0 5

Total 71.9 74.2 15.3 -0.40 0 0

Domain and Total Score Distributions

• Face/Eye and Pain scales skewed secondary to ceiling effects– As long as endorsement rate < 95% and modest

item-item correlations (>0.25), this will not affect the psychometric properties of a scale37,38

Distributions by demographics

f m Age** Years since Dx** Years since Rx**Scale

Anxiety 70.8 74.4 -0.10 -0.06 0.09

Balance 70.7 74.5 -0.21 -0.14 0.00

General 63.8 64.5 -0.31 -0.18 -0.04

Hearing 67.4 62.5 0.03 -0.20 -0.06

Energy 70.1 66.2 -0.24 -0.14 -0.06

Pain 77.0 75.5 0.03 -0.06 -0.04

Eye/face 82.5 87.0 -0.11 -0.24 -0.16

Total 71.8 72.1 -0.18 -0.21 -0.06

*No signficiant differences in mean scores using ANOVA.**Correlations are Pearson product-moment correlation coefficients.

Gender*

Correlation/Distribution of Scale Domains by Demographics

Correlations between domains

Anxiety Balance General Hearing Energy Pain Eye/face

Anxiety 1.00

Balance 0.51 1.00

General 0.49 0.41 1.00

Hearing 0.47 0.50 0.39 1.00

Energy 0.61 0.61 0.59 0.60 1.00

Pain 0.40 0.34 0.28 0.37 0.42 1.00

Eye/face 0.30 0.41 0.10 0.31 0.33 0.23 1.00

Total* 0.66 0.65 0.52 0.62 0.76 0.47 0.37

*Modified total scores that exclude individual domain contributions used for correlations. Correlations are Pearson product-moment correlation coefficients.

Correlations Between Scale Domains

Convergent validity

• Can investigate correlation with SF-36 and global visual analogue scale (VAS) measures

• Other potential indicators more problematic– Size: no difference in QOL5,10,20,24,29,30,33

– H-B: variable to no impact 7,10,13,14,20,29

– PTA/SRT/Discrimination scores: variable to no impact 20 – Balance function tests: do not correlate well with patient-

perceived symptoms or QOL 39 – Surgery: some patients had deterioration, others large

improvement in health status, large changes over time 23,24,29

– Gamma knife: some trends towards deterioration, not statistically significant 29

– Time since surgery: variable to no effect 20,33

Scale/SF-36 correlations

Physical Functioning

Role Physical

Role Emotional Vitality

Mental Health

Social Functioning Pain

General Health

Total Score

Anxiety 0.28 0.35 0.31 0.57 0.59 0.44 0.25 0.39 0.47

Balance 0.49 0.48 0.28 0.55 0.47 0.51 0.30 0.42 0.57

General 0.47 0.51 0.43 0.55 0.46 0.41 0.42 0.61 0.62

Hearing 0.34 0.53 0.38 0.49 0.50 0.51 0.29 0.35 0.52

Energy 0.55 0.53 0.51 0.69 0.57 0.58 0.39 0.56 0.70

Pain 0.29 0.40 0.28 0.43 0.34 0.28 0.42 0.37 0.43

Eye/face 0.17 0.17 0.01 0.24 0.16 0.16 0.20 0.19 0.20

Total 0.53 0.61 0.45 0.72 0.63 0.58 0.47 0.59 0.71

Correlations are Pearson product-moment correlation coefficients. Stronger relationships are shown in bold.

Individual SF-36 Domains

Correlations Between Scale Domains and SF-36 Domains

Scale/SF-36 correlations

•Correlation of total scale score with SF-36 Physical Health and Mental Health Subscale

Scale/VAS correlations

DomainsOveral QOL Dizziness

Facial Function

Emotional Health Hearing Pain ADLs Energy

Anxiety 0.47 0.37 0.27 0.60 0.29 0.33 0.43 0.53

Balance 0.37 0.66 0.40 0.52 0.38 0.36 0.56 0.58

General 0.60 0.32 0.17 0.42 0.24 0.43 0.47 0.55

Hearing 0.35 0.35 0.22 0.45 0.54 0.34 0.46 0.56

Energy 0.42 0.50 0.26 0.58 0.40 0.37 0.58 0.72

Pain 0.21 0.26 0.03 0.24 0.15 0.43 0.47 0.35

Eye/face 0.07 0.22 0.46 0.23 0.09 0.16 0.29 0.20Total 0.49 0.54 0.34 0.61 0.42 0.50 0.66 0.71

Correlations are Pearson product-moment correlation coefficients. Stronger relationships are shown in bold.

Correlations Between Domains and Visual Analog Scale (VAS) Items

Individual VAS Items

House-Brackmann score

I II III IV V VI

Scale

Anxiety 73.7 69.0 66.9 85.0 72.5 NA

Balance 74.5 55.8 70.3 79.2 85.4 NA

General 62.5 60.0 74.0 79.2 75.0 NA

Hearing 64.2 61.3 65.6 78.1 62.5 NA

Energy 68.7 56.7 64.1 81.3 89.6 NA

Pain 75.0 75.0 84.4 100.0 100.0 NA

Eye/face 89.8 65.0 63.5 70.8 66.7 NA p<0.001

Total 72.6 63.3 69.8 81.9 78.8 NA

SF-36

Physical Functioning 76.2 65.6 78.5 94.4 91.7 NA

Role Physical 80.7 80.0 96.9 100.0 100.0 NA

Role Emotional 81.1 93.3 100.0 100.0 100.0 NA

Vitality 68.6 65.0 69.4 87.5 75.0 NA

Mental Health 80.0 77.6 77.5 86.0 90.0 NA

Social Functioning 86.4 82.5 89.1 100.0 100.0 NA

Pain 82.3 85.0 88.1 100.0 100.0 NAGeneral Health 71.5 73.0 63.8 87.5 90.0 NA

Significance testing by ANOVANA = Not applicable (N=0)

Distribution of Scale and SF-36 Domain Scores by House-Brackmann Score

House-Brackmann Score

Audiogram results

PTA SRT DiscrimScale

Anxiety 0.03 0.06 -0.05

Balance -0.04 -0.04 0.04

General -0.02 -0.02 0.03

Hearing -0.20 -0.18 0.16

Energy -0.11 -0.11 0.08

Pain 0.02 0.04 0.03

Eye/face -0.23 -0.23 0.15

Total -0.11 -0.09 0.09

SF-36

Physical Functioning -0.03 -0.05 -0.03

Role Physical -0.01 0.00 -0.02

Role Emotional 0.02 0.03 -0.12

Vitality -0.03 -0.02 -0.06

Mental Health 0.01 0.01 -0.07

Social Functioning 0.00 -0.01 -0.14

Pain 0.08 0.08 -0.04

General Health -0.03 -0.04 -0.01

Correlations are Pearson product-moment correlation coefficients.

Correlation of Scale and SF-36 Domains with PTA, SRT and Speech Discrimination Scores

Size

<1 1-2 >2Scale

Anxiety 70.1 77.0 72.0

Balance 73.1 76.0 69.4

General 62.2 62.8 70.6

Hearing 64.2 68.9 62.3

Energy 68.6 68.3 70.8

Pain 77.3 75.7 80.8

Eye/face 87.2 89.5 77.2 p=0.01

Total 71.8 74.0 71.9

SF-36

Physical Functioning 77.4 75.8 86.1

Role Physical 80.2 84.5 88.3

Role Emotional 79.8 89.7 93.3

Vitality 68.1 70.1 70.8

Mental Health 79.0 81.5 80.8

Social Functioning 85.2 86.4 91.5

Pain 82.4 86.2 87.8

General Health 71.5 67.6 79.8 p<0.05

Significance testing by ANOVA

Distribution of Scale and SF-36 Domain Scores by Size

Size (cm)

Treatment

Conservative (n=54)

Gamma (n=10)

Surgery (n=48)

Scale

Anxiety 72.2 74.0 73.4

Balance 75.5 72.5 70.1

General 60.8 54.2 69.7 p<0.03

Hearing 66.6 63.1 64.2

Energy 69.2 66.7 68.7

Pain 77.8 80.0 77.1

Eye/face 92.3 85.8 77.8 p<0.001

Total 73.5 70.9 71.6

SF-36

Physical Functioning 77.8 68.3 81.1

Role Physical 84.2 60.0 86.5 p<0.05

Role Emotional 84.6 83.3 88.2

Vitality 70.6 69.0 67.5

Mental Health 80.6 81.6 79.2

Social Functioning 86.8 81.9 88.1

Pain 83.2 73.8 88.5

General Health 71.6 58.0 75.5 p<0.05

Significance testing by ANOVA

Distribution of Scale and SF-36 Domain Scores by Treatment Type

Treatment

Discriminative validity

• Our scale is not intended as a diagnostic or screening tool like some in the psychiatric literature– Do not expect difference between similar

groups of patients

• The scale was given to a group of patients presenting to a general otology clinic for comparison

Discriminative validity

Patients (n=117) Controls (n=90) p value*

Age, years 60.4 52.3 p<0.001Range 20-84 16-90 NS

Gender, N (%)Male 55 (47) 44 (51) NSFemale 62 (53) 43 (49) NS

ScaleAnxiety 72.3 66.0 p<0.05Balance 72.5 68.1 NS

General 64.2 60.9 NSHearing 65.1 61.2 NSEnergy 68.3 60.7 p<0.03Pain 76.3 75.3 NSEye/face 84.6 93.8 p<0.001Total 71.9 71.3 NS

SF-36Physical Functioning 78.7 75.1 NSRole Physical 83.3 65.9 NSRole Emotional 86.6 78.2 NSVitality 69.1 65.7 NSMental Health 80.2 76.9 NSSocial Functioning 87.1 74.7 p<0.001Pain 84.4 84.9 NSGeneral Health 72.2 64.3 p<0.03*Using Student's t-test

NS = not significant

Comparison of Scale and SF-36 Domains Between Cases and Controls

Reliability

• Reliability: the scale is measuring something in a reproducible fashion

• Different ways to measure– Internal consistency: based on single

administration• Cronbach’s alpha results already shown• Factor structure also supports reliability

– Stability: test-retest reliability• Part of the ongoing study

Conclusions

• There is a need and demand for a validated, disease-specific QOL measure for acoustic neuroma

• Our QOL measure has validity in terms of face, content, and construct properties

• Internal consistency as one measure of reliability is strong– Test-retest reliability studies are ongoing

Conclusions

• Use of the survey as part of ongoing prospective trials will ultimately do much to prove its validity– Show sensitivity to change over time– Show changes from before/after intervention

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Otorhinolaryngology: Head and Neck Surgery at PENN Excellence in Patient Care, Education and Research since 1870

Special thanks: Michael Ruckenstein, MD

Douglas Bigelow, MD

Jeffrey Staab, MD