Table 1.
Characteristics of the study sample*
| Characteristic | Antidepressants (N=142,767) | Antidiabetics (N=101,841) | Statins (N=318,934) |
|---|---|---|---|
| Demographic and socioeconomic characteristics | |||
| Mean age (SD) | 76.6 (7.9) | 75.4 (7.0) | 75.6 (7.1) |
| Female sex (%) | 73.8 | 53.7 | 58.4 |
| White race (%) | 97.0 | 91.8 | 94.9 |
| Proportion of population in ZIP code who are high school graduate or higher (%) | 87.3 (7.9) | 86.1 (8.3) | 87.3 (8.0) |
| Median household income in $ (SD) † | 57,298 (22,974) | 55,067 (21,546) | 58,115 (23,581) |
| Health services utilization in 2009 | |||
| At least one hospitalization (%) | 27.5 | 22.1 | 19.7 |
| At least one emergency department visit (%) | 38.4 | 30.2 | 27.7 |
| At least one prescription by mail order (%) | 10.0 | 13.1 | 14.7 |
| At least one specialist visit (%) | 7.6 | 6.7 | 14.7 |
| Health status | |||
| RxHCC score (SD)‡ | 1.13 (0.42) | 1.17 (0.35) | 1.02 (0.35) |
| End-stage renal disease (ESRD) (%) | 0.55 | 0.52 | 0.48 |
| Disease-specific comorbidities | |||
| Delirium, dementia, and amnestic and other cognitive disorders (%) | 17.2 | ||
| Anxiety disorders (%) | 20.2 | ||
| Bipolar disorders (%) | 2.9 | ||
| Depressive disorders (%) | 38.0 | ||
| Schizophrenia and other psychotic disorders (%) | 5.0 | ||
| Diabetic neuropathy (%) | 15.0 | ||
| Diabetic nephropathy (%) | 5.8 | ||
| Diabetic retinopathy (%) | 15.4 | ||
| Diabetes with peripheral vascular disease (%) | 8.4 | ||
| Insulin use during the year (%) | 15.0 | ||
| Hyperlipidemia (%) | 84.2 | 92.2 | |
| Type 2 diabetes (%) | 97.4 | 34.6 | |
| Coronary heart disease (%) | 39.9 | ||
| Stroke/TIA (%) | 8.3 | ||
| Medication use in the year (%) | |||
| Only generic drugs | 73.4 | 70.4 | 58.7 |
| Only brand drugs | 17.3 | 9.5 | 35.1 |
| Both generic and brand drugs | 9.3 | 20.1 | 6.2 |
*
Figures with parentheses are means and SDs.
†
Household income is based on the median income of the patient's geographic area according to ZIP code and 2010 U.S. Census data.
‡
Prescription-drug Hierarchical Condition Category (RxHCC) scores are based on diagnoses from 2009 inpatient, outpatient, carrier, hospice, and home health agencies claims and are normalized to equal 1.00 on average for all Medicare Part D enrollees, with a range in the study sample of 0.37 to 5.90. Higher scores indicate an increase likelihood of higher drug spending and poorer health status.