Table 5:
The Influence of Payments on Target Drug Prescription Volume: Robustness Checks
|
Dependent Variable:
Number of Prescribed Patients |
|||||
|---|---|---|---|---|---|
| Specification: | |||||
| Baseline | HRR-drug-quarter Fixed Effects | Controls for Other Payments | Matched Sample, Flexible Trends | Matched Sample, Without Trends | |
| (1) | (2) | (3) | (4) | (5) | |
| Payment Count, by Type | |||||
| Own Compensation | 0.3684 (0.1156) | 0.3664 (0.1104) | 0.3679 (0.1146) | 0.4184 (0.1474) | 0.4948 (0.1224) |
| Own Food | 0.0584 (0.0037) | 0.0557 (0.0036) | 0.0561 (0.0037) | 0.0668 (0.0064) | 0.0676 (0.0047) |
| Peer Compensation | 0.0197 (0.0061) | 0.0192 (0.0060) | 0.0245 (0.0060) | 0.0249 (0.0077) | 0.0289 (0.0055) |
| Peer Food | −0.0006 (0.0014) | −0.0012 (0.0013) | −0.0014 (0.0013) | −0.0030 (0.0027) | −0.0071 (0.0022) |
| Mean dependent variable | 0.5486 | 0.5488 | 0.5486 | 0.7750 | 0.7750 |
| N (Doctor × Drug × Quarter) | 5,466,420 | 5,463,264 | 5,466,420 | 1,913,556 | 1,913,556 |
Notes: Table compares estimates obtained from different variants of equation (2). Column 1 repeats our baseline estimates of the effects of payments of different types on the quarterly number of prescribed beneficiaries, already shown in Table 3. Column 2 shows an extended specification that includes HRR-drug-quarter fixed effects, in addition to all terms of the baseline specification (HRR is missing for a small number of observations, hence the slightly smaller sample size). Column 3 shows an extended specification that includes separate controls for payments made by the pharmaceutical company that promotes the target drug in association with any other drugs except for the target drug. Columns 4 and 5 show alternative estimates of the effects of payments on prescriptions, obtained using a sample that includes recipients of compensation payments and matched non-recipients. Matching was first performed exactly on specialty and drug then coarsely on group practice network degree, shared-patient network degree, and years of experience. Details of the matching procedure are described in Appendix Section A.2 and Appendix Table A8. Physician-drug, specialty-drug-quarter fixed effects, controls for all other types of payments, and payment-type-specific linear time trends included in all specifications. Standard errors are clustered within doctor. Column 5 excludes differential time trends for doctors paid during our Medicare Part D sample period.