Figure 1.

Cohort construction. Analysis of prescription fills for three chronic drug categories: antihyperlipidemics, antihypertensives, and oral hypoglycemic. For each subject, prescription fills for the same drug were sequenced temporally into drug eras. Drug eras were excluded from analysis if there were: (1) gaps in membership in the insurance plan during the first year of prescriptions; (2) drug eras that began before a 6-month wash-out period, or in the last 13 months of the dataset (left and right censoring); (3) hospitalizations during the first year of prescriptions; and (4) unusual age, gender, and fill quantities likely due to human errors during data entry.