Table 4.
Panel regressions of biosimilar share by drug (class), all physicians, and balanced panel, 2009–2015.
| ESA | Filgrastim | Somatropin | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| All Physicians | Balanced Panel | All Physicians | Balanced Panel | All Physicians | Balanced Panel | |||||
| GP | specialist | GP | specialist | GP | specialist | specialist | GP | specialist | specialist | |
| Priority prescribing | −0.0263 | −0.0069 | −0.0776 | −0.0129 | −0.0104 | −0.0331 *** | −0.0180 | 0.0095 | −0.0077 | −0.0199 |
| (0.0202) | (0.0083) | (0.0665) | (0.0106) | (0.0270) | (0.0097) | (0.0230) | (0.0157) | (0.0069) | (0.0105) | |
| Quota | −0.0260 * | −0.0098 * | 0.0924 * | 0.0178 ** | −0.0356 | 0.0612 ** | 0.0411 | −0.0087 | 0.0152 | 0.0118 |
| (0.0105) | (0.0046) | (0.0359) | (0.0056) | (0.0735) | (0.0220) | (0.0589) | (0.0141) | (0.0083) | (0.0138) | |
| Group practice (ref: solo practice) | 0.0153 * | 0.0502 *** | −0.0434 * | 0.0241 *** | 0.1081 *** | 0.0967 *** | 0.0695 *** | −0.0250 ** | −0.0053 | −0.0405 *** |
| (0.0069) | (0.0031) | (0.0181) | (0.0041) | (0.0159) | (0.0062) | (0.0149) | (0.0093) | (0.0056) | (0.0091) | |
| Share of patients receiving biologic drug in practice | 2.6378 *** | 1.9431 *** | 3.9994 *** | 2.2698 *** | 8.4402 *** | 1.8534 *** | 7.1655 *** | 14.0649 | 2.9614 *** | 3.8537 *** |
| (0.2882) | (0.0390) | (0.3167) | (0.0480) | (1.7605) | (0.1609) | (1.5168) | (8.3375) | (0.4713) | (0.4650) | |
| Patient age | 0.0021 *** | 0.0020 *** | −0.0032 | −0.0009 | 0.0064 *** | 0.0041 *** | −0.0044 | −0.0004 | −0.0010 *** | 0.0002 |
| (0.0004) | (0.0003) | (0.0033) | (0.0006) | (0.0010) | (0.0008) | (0.0025) | (0.0004) | (0.0002) | (0.0006) | |
| Comorbidity index | −0.0001 | 0.0017 ** | 0.0017 | −0.0011 | 0.0041 | 0.0062 *** | −0.0014 | −0.0015 * | −0.0023 ** | −0.0054 * |
| (0.0006) | (0.0006) | (0.0024) | (0.0009) | (0.0022) | (0.0012) | (0.0041) | (0.0007) | (0.0009) | (0.0023) | |
| Share male individuals of biologic patients | −0.0068 | −0.0207 * | 0.0117 | −0.0500 * | −0.0193 | −0.1019 *** | −0.2175 *** | −0.0087 | −0.0148 | −0.0483 |
| (0.0082) | (0.0091) | (0.0947) | (0.0213) | (0.0251) | (0.0126) | (0.0443) | (0.0096) | (0.0094) | (0.0272) | |
| Share individuals older 65 years of age of biologic patients | −0.0144 | 0.0383 *** | 0.4178 *** | 0.1494 *** | −0.0114 | −0.0127 | 0.0417 | −0.0156 | 0.0149 | −0.0479 |
| (0.0114) | (0.0116) | (0.1072) | (0.0233) | (0.0354) | (0.0211) | (0.0760) | (0.0145) | (0.0172) | (0.0437) | |
| Number of patients in practice in 1000 patients | 0.0054 | 0.0182 *** | 0.0445 *** | 0.0478 *** | −0.0091 | 0.0154 *** | 0.0647 *** | 0.0157 *** | 0.0051 ** | 0.0099 *** |
| (0.0033) | (0.0015) | (0.0105) | (0.0027) | (0.0063) | (0.0023) | (0.0116) | (0.0031) | (0.0016) | (0.0025) | |
| Price per DDD of packages prescribed by physician | −0.0014 | −0.0003 *** | −0.0155 *** | −0.0003 | −0.0006 *** | −0.0008 *** | −0.0020 *** | −0.0003 * | −0.0008 *** | −0.0013 *** |
| (0.0011) | (0.0001) | (0.0037) | (0.0003) | (0.0001) | (0.0001) | (0.0002) | (0.0001) | (0.0001) | (0.0001) | |
| Average household income in region of practice in 1000 EUR | −0.0146 | 0.1053 *** | −0.4648 *** | 0.1230 *** | 0.2550 ** | 0.3196 *** | 0.1587 | 0.1009 ** | −0.1499 *** | −0.2061 *** |
| (0.0384) | (0.0156) | (0.1164) | (0.0204) | (0.0867) | (0.0318) | (0.0812) | (0.0343) | (0.0252) | (0.0416) | |
| Urbanized areas (ref: metropolitan) | −0.0056 | 0.0351 *** | 0.0624 ** | 0.0440 *** | −0.1306 *** | −0.0087 | 0.0540 * | 0.0283 * | 0.0036 | −0.0434 *** |
| (0.0078) | (0.0035) | (0.0207) | (0.0045) | (0.0197) | (0.0071) | (0.0225) | (0.0110) | (0.0053) | (0.0092) | |
| Rural (ref: metropolitan) | −0.0233 | 0.0795 *** | 0.0328 | 0.0777 *** | −0.1085 ** | 0.0229 * | 0.1099 *** | 0.0128 | −0.0633 *** | −0.0970 *** |
| (0.0127) | (0.0055) | (0.0480) | (0.0069) | (0.0340) | (0.0113) | (0.0254) | (0.0132) | (0.0078) | (0.0100) | |
| TIME Fixed Effects | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Physician Association Fixed Effects | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Intercept | 0.1310 | −0.1684 *** | 0.7707 ** | −0.0614 | −0.3750 * | −0.2740 ** | 0.8661 *** | −0.1694 ** | 0.3906 *** | 0.7799 *** |
| (0.0692) | (0.0305) | (0.2545) | (0.0448) | (0.1622) | (0.0850) | (0.2267) | (0.0639) | (0.0459) | (0.0753) | |
| N | 15,506 | 50,389 | 1074 | 23,258 | 3021 | 14,758 | 1607 | 1.436 | 7392 | 2569 |
| r2 | 0.070 | 0.319 | 0.537 | 0.456 | 0.308 | 0.247 | 0.504 | 0.186 | 0.216 | 0.376 |
| F | 13.339 | 313.778 | 58.227 | 312.700 | 25.908 | 66.053 | 93.470 | 3.877 | 27.386 | 23.007 |
| RMSE | 0.3568 | 0.2857 | 0.2041 | 0.2396 | 0.3768 | 0.3307 | 0.2594 | 0.1305 | 0.1675 | 0.1481 |
ESA: Erythropoesis stimulating agents; GP: general practitioner; ***: p < 0.01; **: p < 0.05; *: p < 0.1, standard errors are in parantheses; The balanced panel includes physicians prescribing the target biologic drug in each quarter 2009–2015.