GAPS IN CARDIOVASCULAR MEDICATION TAKING - THE TIP OF THE ICEBERG

Objective: To search for major gaps in medication-taking behavior pred isposing patients to cardiovascular morbidity and mortality. Design: C onvenience sample; cohort prospectively followed for less-than-or-equa l-to 5 months. Setting: General internal medicine and cardiology clini cs in a university medical center. Patients: From among 893 patients, the authors identified 132 eligible individuals and entered 33 subject s (25%) with chronic cardiovascular conditions, 1 - 3 chronic oral med ications for these conditions, overall regimen of less-than-or-equal-t o 6 drugs, regular visits at 1 -3-month intervals, literacy in English , willingness to use electronic monitors, and physician permission to participate. Outcome measures: Medication compliance rates and pattern s by patient self-report, physician estimates, pill count, and electro nic monitoring of pill vial opening. Results: Despite moderately compl ex regimens (5.4 +/- 0.5 pills daily; range 1 - 11), most subjects too k most medications according to the prescription: median intervals bet ween pill vial openings were 1.00, 0.50, and 0.43 days for once, twice , and three times daily dosing, respectively. Medication-taking gaps o f greater-than-or-equal-to 2 times the prescribed interdosing interval occurred for 48% of the patients. Patients' dosing patterns often pro duced ''uncovered'' intervals (mean duration 3.7 days, range 0 - 2 5) with doubtful pharmacologic effectiveness. These lapses were underesti mated by patients and poorly perceived by their treating physicians, d espite familiarity with their care. Baseline sociodemographic, psychos ocial, medical system, or clinical characteristics did not predict the patterns or degrees of medication noncompliance. Conclusions: Major t reatment gaps occur frequently, even in carefully selected ambulatory populations, and generally escape detection. The compliance patterns a nd gaps may contribute to reported excesses of cardiovascular morbidit y and mortality.