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Journal Club

Alcohol, Other Drugs, and Health: Current Evidence

May–June 2010

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Featured Article

β-Blockers for Chest PainAssociated with

Recent Cocaine Use

Rangel C, et al. Arch Intern Med. 2010;170(10):874 –9.

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Study Objective

• To determine whether β-blockers, which are known to decrease adverse events after myocardial infarction but are thought to be potentially harmful following recent cocaine use, are safe for patients with cocaine-related chest pain.

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Study Design

• Retrospective cohort study of consecutive patients admitted to San Francisco General Hospital with chest pain and cocaine-positive urine test results between January 2001 and December 2006 (N=331).

• Mortality data were collected from the Department of Health & Human Services National Death Index.

• The primary predictor was receipt of a β-blocker in the Emergency Department (ED). Secondary predictors were receipt of any β-blocker during post-ED hospitalization and discharge on a β-blocker regimen.

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Study Design (cont’d)

• The primary outcome measure was death. Secondary outcomes were:

– peak troponin level in the first 24 hours of

admission

– ventricular fibrillation or ventricular

tachycardia requiring defibrillation

– need for intubation

– need for vasopressor agents

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Assessing Validity of an Article About Harm

• Are the results valid?

• What are the results?

• How can I apply the results to patient care?

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Are the Results Valid?

• Did the investigators demonstrate similarity in all known determinants of outcomes? Did they adjust for differences in the analysis?

• Were exposed patients equally likely to be identified in the two groups?

• Were the outcomes measured in the same way in the groups being compared?

• Was follow-up sufficiently complete?

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Did the investigators demonstrate similarity in all known determinants

of outcomes? Did they adjust for differences in the analysis?

• Yes.– Covariables were included in the multivariable

model based on convention (e.g., age and sex) or if they were associated with both the predictor and outcome with a p-value of <.20.

– Analyses were adjusted for the following:–age, race, and sex–history of end-stage

renal disease–outpatient angiotensin-converting enzyme

inhibitoruse

–outpatient angiotensin-receptor blocker use–troponin level–discharge on a calcium

channelblocker regimen

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Were exposed patients equally likely

to be identified in the groups?

Yes.

– Exposure for all subjects was documented in paper medical charts and in electronic medical records.

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Were the outcomes measured in the same way in the groups being

compared?

Yes.

– The National Death Index was used to determine deaths (primary outcome) that occurred after admission among all subjects.

– Data on secondary outcomes were obtained from paper medical charts and the electronic medical record.

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Was follow-up sufficiently complete?

• Yes.

– Information was available from the National Death Index for 317 of 331 subjects (96%) at 5-year follow-up.

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What are the Results?

• How strong is the association between exposure and outcomes?

• How precise is the estimate of the risk?

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How strong is the association between exposure and outcome?

How precise is the estimate of the risk?

• The researchers were not able to detect an association between receipt of a β-blocker and incident mortality:

– received a β-blocker in the ED (hazard ratio [HR], 0.97; 95% CI, 0.53–1.79).

– received a β-blocker during hospitalization (HR, 0.81; 95% CI, 0.44 –1.48).

– discharged on a β-blocker regimen (HR, 0.90; 95% CI, 0.47–1.71).

• Discharge on a β-blocker regimen was associated with a significant (70%) reduction in the risk of cardio-vascular death (HR, 0.29; 95% CI, 0.09–0.98).

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How Can I Apply the Results to Patient Care?

• Were the study patients similar to the patients in my practice?

• Was the duration of follow-up adequate?

• What was the magnitude of the risk?

• Should I attempt to stop the exposure?

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Were the study patients similar to the patients in my practice?

• Subjects were predominantly black males and were approximately 50 years of age.

• More than 80% were current smokers.

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Was the duration of follow-up adequate?

• Yes.

– Five years is an adequate period of time for follow-up of cardiovascular mortality and effects of β-blocker exposure.

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What was the magnitude of the risk?

• The researchers were unable to determine whether β-blockers placed patients with cocaine-related chest pain at increased risk of mortality:

– received a β-blocker in the ED (hazard ratio [HR], 0.97; 95% CI, 0.53-1.79).

– received a β-blocker during hospitalization (HR, 0.81; 95% CI, 0.44-1.48).

– discharged on a β-blocker regimen (HR, 0.90; 95% CI, 0.47-1.71).

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Should I attempt to stop the exposure?

• The findings do not support limiting β-blocker treatment in patients with cocaine-related chest pain due to concerns over unopposed alpha-adrenergic stimulation.

• The findings are limited by the following:– lack of blinding.– potential surveillance bias (only patients with

cocaine-metabolite–positive urine tests were included in the study).