Table 1.
Study populations
| Attrition Steps | Number | Percent |
|---|---|---|
| 25% random sample of AARP Medicare Supplement insureds | 1,082,348 | 100 |
| With Medicare Part D prescription drug claims in 2014–2016 | 446,192 | 41 |
| With back pain diagnosis codes in 2015 | 125,458 | 28 |
| Apply exclusion based on HEDIS rules* | 42,502 | 10 |
| Exclude age younger than 64 y | 41,508 | 9 |
| 12 mo of enrollment following index low back pain diagnosis | 40,426 | 9 |
| 12 mo of enrollment before index low back pain diagnosis | 37,897 | 8 |
| Final study population | 37,897 | 100 |
| New back pain patients | 20,645 | 54 |
| Recurring back pain patients | 17,252 | 46 |
HEDIS = Healthcare Effectiveness Data and Information Set.
*
HEDIS exclusion diagnosis codes: malignant neoplasms, other neoplasms, history of malignant neoplasm, trauma, intravenous drug abuse, neurologic impairment, and HIV.