Table 1.
Characteristics of Articles Investigating Patient Cost-Sharing Amount and Medication Adherence
| Concept studied | |
| Impact of cost sharing on adherence | 44 (67%) |
| Impact of cost sharing on adherence and outcomes | 22 (33%) |
| Study design | |
| Retrospective | 56 (85%) |
| Prospective | 9 (14%) |
| Cross-sectional | 1 (2%) |
| Population studied | |
| Commercially insured | 57 (86%) |
| Medicare, other publicly insured | 9 (14%) |
| Treatment or disease area studied | |
| Cardiovascular | 20 (31%) |
| Diabetes | 5 (7%) |
| Mental health | 3 (4%) |
| Pulmonary | 3 (4%) |
| Arthritis | 2 (3%) |
| Infectious disease | 1 (2%) |
| Gastrointestinal disease | 2 (3%) |
| General | 30 (46%) |
| Adherence: operational definition | |
| Number of filled prescriptions over a set time period | 25 (38%) |
| Medication possession ratio (MPR) | 20 (30%) |
| Combination of number of refills and medication possession ratio | 2 (4%) |
| Patient self-report | 10 (15%) |
| Other (i.e., initiation, discontinuation, elasticity) | 8 (12%) |
| Relationship between cost sharing and adherence | |
| Statistically significant, inverse relationship | 56 (85%) |
| No relationship or no statistically significant relationship | 10 (15%) |