Table 3.
Logistic Regression Results--Estimated Effects of Plan Features on the Use of Generic Drugs*
| Variables | Adjusted Odds Ratios (95% CI) |
||
|---|---|---|---|
| Antidepressants | Antidiabetics | Statins | |
| Plan cost-sharing features | |||
| Cost-sharing for a generic drug ($) | 0.97 (0.95-0.98)† | 0.97 (0.96-0.98)† | 0.94 (0.92-0.95)† |
| Cost-sharing difference between brand and generic drugs ($) | 1.01 (1.01-1.02)† | 1.01 (1.01-1.02)† | 1.02 (1.01-1.02)† |
| Utilization management tools | |||
| Prior authorization (ref=no) | |||
| Yes | 1.29 (1.15-1.44)† | 1.14 (1.09-1.20)† | 1.12 (1.00-1.27)† |
| Step therapy (ref=no) | |||
| Yes | 1.07 (1.02-1.13)† | 1.04 (0.99-1.09) | 1.13 (1.08-1.19)† |
| Other plan features | |||
| Deductible (ref=yes) | |||
| No | 1.10 (1.01-1.19)† | 1.09 (1.01-1.19)† | 1.45 (1.33-1.58)† |
| Gap coverage (ref=no) | |||
| Yes | 1.09 (0.90-1.30) | 1.03 (0.86-1.24) | 1.24 (1.04-1.47)† |
| Premium ($, ref=$1-<30) | |||
| $30-50/month | 0.90 (0.84-0.96)† | 1.08 (1.00-1.17) | 0.75 (0.69-0.81)† |
| $50+/month | 0.79 (0.66-0.95)† | 0.84 (0.69-1.02) | 0.56 (0.46-0.67)† |
| Demographic and socioeconomic characteristics | |||
| Sex (ref=male) | |||
| Female | 0.94 (0.91-0.97)† | 1.14 (1.10-1.18)† | 1.08 (1.06-1.10)† |
| Race/ethnicity (ref=other) | |||
| Non-Hispanic white | 0.81 (0.75-0.88)† | 1.00 (0.94-1.06) | 0.95 (0.91-0.98)† |
| Age group (year, ref=65-74) | |||
| 75-84 | 1.05 (1.02-1.09)† | 0.99 (0.95-1.03) | 1.01 (1.00-1.03) |
| 85+ | 1.04 (1.00-1.09)† | 0.94 (0.89-1.00) | 1.10 (1.07-1.13)† |
| Education (%, ref=other) | |||
| High school graduate or higher | 0.99 (0.99-0.99)† | 1.00 (0.99-1.00)† | 1 .00(0.99-1.00)† |
| Median household income ($) | 1.00 (1.00-1.00)† | 1.00 (1.00-1.00)† | 1.00 (1.00-1.00)† |
| Health services utilization | |||
| At least one hospitalization (ref=no) | |||
| Yes | 1.06 (1.02-1.10)† | 1.04 (0.99-1.09) | 1.09 (1.07-1.12)† |
| At least one emergency department visit (ref=no) | |||
| Yes | 1.02 (0.99-1.06) | 1.03 (0.98-1.07) | 1.05 (1.03-1.07)† |
| At least one prescription by mail order (ref=no) | |||
| Yes | 1.15 (1.08-1.22)† | 0.94 (0.88-1.01) | 1.15 (1.07-1.24)† |
| At least one prescription by specialist prescribers (ref=no) | |||
| Yes | 0.81 (0.76-0.85)† | 0.60 (0.57-0.64)† | 0.82 (0.81-0.84)† |
| Health status | |||
| RxHCC score | 0.89 (0.86-0.93)† | 1.05 (1.00-1.11) | 1.27 (1.23-1.31)† |
| ESRD (ref=no) | |||
| Yes | 1.19 (0.98-1.43) | 0.65 (0.54-0.79)† | 0.99 (0.88-1.10) |
| Disease-specific comorbidities | |||
| Antidepression specific predictors | |||
| Delirium, dementia, and amnestic and other cognitive disorders (ref=no) | |||
| Yes | 0.88 (0.85-0.91)† | ||
| Anxiety disorders (ref=no) | |||
| Yes | 1.00 (0.96-1.03) | ||
| Bipolar disorders (ref=no) | |||
| Yes | 0.97 (0.90-1.04) | ||
| Depressive disorders (ref=no) | |||
| Yes | 0.72 (0.70-0.74)† | ||
| Schizophrenia and other psychotic disorders (ref=no) | |||
| Yes | 1.07 (1.01-1.13)† | ||
| Antidiabetes specific predictors | |||
| Diabetic neuropathy (ref=no) | |||
| Yes | 0.96 (0.92-1.01) | ||
| Diabetic nephropathy (ref=no) | |||
| Yes | 0.76 (0.71-0.81)† | ||
| Diabetic retinopathy (ref=no) | |||
| Yes | 0.83 (0.79-0.86)† | ||
| Diabetes with peripheral vascular disease (ref=no) | |||
| Yes | 0.99 (0.93-1.05) | ||
| Insulin use during the year (ref=no) | |||
| Yes | 0.85 (0.81-0.89)† | ||
| Hyperlipidemia (ref=no) | |||
| Yes | 0.89 (0.85-0.94)† | ||
| Type 2 diabetes (ref=no) | |||
| Yes | 0.68 (0.61-0.77)† | ||
| Statins specific predictors | |||
| Coronary heart disease (ref=no) | |||
| Yes | 0.76 (0.75-0.78)† | ||
| Stroke/TIA (ref=no) | |||
| Yes | 1.03 (1.00-1.06)† | ||
| Hyperlipidemia (ref=no) | |||
| Yes | 0.87 (0.84-0.90)† | ||
| Type 2 diabetes (ref=no) | |||
| Yes | 1.00 (0.99-1.03) | ||
*
Regression results were adjusted for HRR indicators.
†
Statistically significant odds ratios, p<0.05.