Journal Club Alcohol, Other Drugs, and Health: Current Evidence January–February 2009

Featured Article Alcohol screening scores and medication nonadherence Bryson CL, et al. Ann Intern Med. 2008;149(11):795–804.

Study Objective To identify whether alcohol misuse is associated with increased risk for medication (statin, oral hypoglycemic, or antihypertensives) nonadherence.

Study Design Secondary analysis of cohort data collected prospectively as part of a randomized controlled trial. Participants included: –5473 patients taking a statin. –3468 patients taking oral hypoglycemic agents. –13,729 patients taking antihypertensive medications. All participants had completed the Alcohol Use Disorders Identification Test—Consumption (AUDIT-C).

Study Design (cont’d) Based on AUDIT-C scores, patients were categorized as –Nondrinkers (AUDIT-C = 0) –Low-level alcohol use (AUDIT-C = 1 to 3) –Mild alcohol use (AUDIT-C = 4 to 5) –Moderate alcohol use (AUDIT-C = 6 to 7) –Severe alcohol use (AUDIT-C = 8 to 12) Adherence * was calculated over 2 observation periods: –90 days from the date surveys were received. –1 year from the date surveys were received. *defined as having medications available for at least 80% of the observation period based on pharmacy refill records.

Assessing Validity of an Article About Harm Are the results valid? What are the results? How can I apply the results to patient care?

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?

Did the investigators demonstrate similarity in all known determinants of outcomes? Did they adjust for differences in the analysis? Analyses were adjusted for the following potential confounders: –race –gender –education –marital status –number of medications prescribed (regimen complexity) –smoking status –depression

Were exposed patients equally likely to be identified in the groups?  Validated screening tests for alcohol use and depression were applied in a standard fashion to all subjects in the study.

Were the outcomes measured in the same way in the groups being compared?  Yes. –Medication adherence was measured in a standard fashion using pharmacy refill data. Subjects were considered to be adherent if they had medication from the pharmacy for at least 80% of the observation period

Was follow-up sufficiently complete? Yes. –Follow-up data were obtained on all participants at 90 days and 1 year.

What are the Results? How strong is the association between exposure and outcomes? How precise is the estimate of the risk?

What are the Results? Unhealthy alcohol use was significantly associated with lower adherence to both statin and antihypertensive medications at 1 year. Adherence (adjusted for confounders) was: –66% for nondrinkers. –63% for those with mild unhealthy use. –58% for those with moderate unhealthy use. –55% for those with severe unhealthy use. Despite a similar trend, alcohol categories were not significantly associated with decreased adherence to hypoglycemic medication.

How strong is the association between exposure and outcome? Association between AUDIT-C Scores and Proportion of Patients Adherent to Medication at 1 Year *Number of patients in regression models varies because of missing covariates. †p<0.05 compared with nondrinkers. Variable AUDIT-C score Fully Adjusted Proportion (95% CI) Statin cohort (n=4989)*0 1–3 4–5 6–7 8–12 66 (64–68) 63 (60–65) 63 (59–67) 58 (52–65)† 55 (47–63)† Oral hypoglycemic cohort (n=3114)* 0 1–3 4–5 6–7 8–12 63 (61–65) 60 (57–63) 63 (57–70) 61 (51–70) 58 (48–67) Hypertension treatment cohort (n=12,545)* 0 1–3 4–5 6–7 8–12 64 (63–65) 62 (61–64) 61 (58–64 )† 60 (56–63 )† 56 (52–60 )†

How precise is the estimate of the risk? The confidence intervals are wide, especially for the more severe drinking categories, but lack overlap between nondrinkers and those with the most severe drinking categories for adherence to statins and antihypertensive medications.

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?

Were the study patients similar to the patients in my practice? All patients were veterans. >95% were men. Mean age was 64. >75% were white.

Was the duration of follow-up adequate? Yes. –One would expect to see an impact on adherence within one year.

What was the magnitude of the risk? There was an approximately 10% drop in (statin and antihypertensive) medication adherence between nondrinkers and those with severe alcohol use. There was a linear dose-response impact of increasing alcohol problems resulting in decreased medication adherence. The caveat is no data were provided on clinical outcomes (e.g., lipid levels, glycemic control, blood pressure).

Should I attempt to stop the exposure? Yes. –These data provide evidence for the potential adverse impact of alcohol consumption on medication adherence. Further studies on this association and clinical markers would strengthen the argument to intervene to reduce harm, especially in cases of severe alcohol misuse.