Choudhry 2011.

Methods	Randomized controlled trial
Participants	The study location was Harford, Connecticut, USA 2845 participants were randomized to the intervention group and 3010 participants were randomized to the control group The inclusion criteria were having received both medical and prescription drug benefits through Aetna, discharged from the hospital with a principal or secondary diagnosis code of International Classification of Diseases, 9th Revision, Clinical Modification (ICD‐9‐ CM) 410 (except when the fifth digit was 2) and a length of stay of 3 to 180 days The exclusion criteria were enrollment in a health savings account, 65 years of age or older, plan sponsor has opted out of the study, and receive only medical services or pharmacy coverage but not both through Aetna
Interventions	Intervention: FULL PRESCRIPTION COVERAGE The intervention involved changing the pharmacy benefits of the intervention group patients so that they had no cost sharing for any brand or generic statin, beta‐blocker, ACE inhibitor or ARB for every prescription after randomization Control: USUAL PRESCRIPTION COVERAGE Control patients received usual prescription‐drug coverage
Outcomes	The measures of adherence were medication possession ratios (i.e. the number of days a patient had a supply of each medication class available, divided by the number of days of eligibility for that medication) and proportion of patients with full adherence (defined as a medication possession of = 80%). The data were sourced from the medical coverage provider's database The patient outcomes were "a composite of the first readmission for a major vascular event or coronary revascularization, first major revascular event and health expenditure". All the data were sourced from the insurance company database
Notes	―
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Use of random number generator. (pg 2089) "...randomly assigned to full coverage (full‐coverage group) or usual pharmacy benefits (usual‐coverage group) with the use of a random‐number generator, and all subsequently eligible patients of that plan sponsor were assigned to the same group."
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgment of 'Low risk' or 'High risk' of bias ‐ (pg s33) "When a newly eligible post‐MI patient is identified, an investigator blinded to the identity of the plan sponsor will determine whether that patient's plan sponsor has previously been randomized, and if not, the plan sponsor's block assignment. Plan sponsors will be randomly assigned in a 1:1 ratio to intervention or control using a random number generator. All subsequent patients of that plan sponsor will be assigned to the same group."
Selective reporting (reporting bias)	Low risk	None detected, protocol available
Other bias	Unclear risk	(pg 2096) "Several limitations of our study should be acknowledged. We relied on administrative claims to identify patients and evaluate outcomes. The use of such data for the outcomes that were studied has been validated, and we did not adjudicate study events with medical records. We recruited patients with hospital discharge claims that take time to become available in administrative databases. During the resultant delay, some patients may have become nonadherent to their prescribed therapies. Although this approach increases the generalizability of our findings to other insurers that seek to institute similar plans, it may have diminished the observed effect of the intervention. We evaluated relatively young patients who had been discharged from the hospital after myocardial infarction and who were covered by a large national insurer, and our results may not be generalizable to patients with other conditions or to those who receive health benefits through other means. We do not report the effect of eliminating copayments on the rate of out‐of‐hospital deaths from cardiovascular causes, since such rates will be ascertained by means of data from death certificates recorded in the Centers for Disease Control and Prevention National Death Index (NDI), for which there is a lag between the date of death and its documentation in the NDI. The clinical outcomes we report include only verifiable deaths from cardiovascular causes (i.e., those that occurred during the course of a hospital admission)."
Blinding of outcome assessment (detection bias) Adherence measure	Low risk	(PRIMARY) MEDICATION ADHERENCE RATE ‐ Data sourced from electronic database of the drug coverage company. Objective outcome
Blinding of outcome assessment (detection bias) Patient outcome	Low risk	(PRIMARY) COMPOSITE OF FIRST MAJOR VASCULAR EVENT OR CORONARY REVASCULARIZATION ‐ Objective data retrieved from health records
Blinding of participants (performance bias) Adherence measure	High risk	(PRIMARY) MEDICATION ADHERENCE RATE ‐ Participants were not blinded to the study. "Patients in the full‐coverage group were also informed of the change in their pharmacy benefits." (pg 2090)
Blinding of participants (performance bias) Patient outcome	Low risk	(PRIMARY) COMPOSITE OF FIRST MAJOR VASCULAR EVENT OR CORONARY REVASCULARIZATION ‐ Objective data retrieved from health records
Blinding of personnel (performance bias) Adherence measure	Low risk	(PRIMARY) MEDICATION ADHERENCE RATE ‐ Data sourced from electronic database of the drug coverage company. Objective outcome
Blinding of personnel (performance bias) Patient outcome	Low risk	(PRIMARY) COMPOSITE OF FIRST MAJOR VASCULAR EVENT OR CORONARY REVASCULARIZATION ‐ Objective data retrieved from health records
Incomplete outcome data (attrition bias) Adherence measure	Low risk	(PRIMARY) MEDICATION ADHERENCE RATE ‐ Rate of missing data balanced. ITT analysis done
Incomplete outcome data (attrition bias) Patient outcome	Low risk	(PRIMARY) COMPOSITE OF FIRST MAJOR VASCULAR EVENT OR CORONARY REVASCULARIZATION ‐ Rate of missing data balanced. ITT analysis performed