ABSTRACT
OBJECTIVE: to determine the frequency and risk factors of non-compliance to oral metronidazole. STUDY DESIGN: comparative cross-sectional survey. STUDY UNITS: 111 patients who received oral metronidazole. SETTING CHARACTERISTICS: two medical units: one primary level unit and one secondary care unit of the Mexican Institute of Social Security. MEASUREMENTS: non-compliance was assessed by home interview and pill count. MAIN RESULTS: frequency of non-compliance was 55%. Risk factors for non-compliance were: female sex (OR = 3.0; p less than 0.05); side effects (OR = 3.1; p less than 0.05); low literacy (OR = 3.75; p less than 0.05). Stratified analysis showed no interaction between variables. CONCLUSIONS: frequency of non-compliance to metronidazole is high, and could affect the effectiveness of medical care. Female patients with low literacy and who suffer side effects are a high risk group for non-compliance.