Table 1.
Descriptive statistics pre- and post-matching
| Pre-matching | Post-matching | |||||
|---|---|---|---|---|---|---|
| Continuous users | Switchers | P value | Continuous users | Switchers | P value | |
| Sample size | 25,363 | 10,080 | 9925 | 9925 | ||
| Demographics | ||||||
| Age, mean (SD) | 49.8 (10.5) | 50.8 (10.1) | 0.0000 | 51.2 (10.1) | 50.8 (10.1) | 0.0006 |
| Sex, n (%) | 0.0000 | 0.0873 | ||||
| Male | 4065 (16.0) | 1852 (18.4) | 1906 (19.2) | 1812 (18.3) | ||
| Female | 21,295 (84.0) | 8228 (81.6) | 8019 (80.8) | 8113 (81.7) | ||
| Unknown | 3 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| Region, n (%) | 0.0000 | 0.0000 | ||||
| Northeast | 2519 (9.9) | 857 (8.5) | 757 (7.6) | 843 (8.5) | ||
| Midwest | 4122 (16.3) | 1691 (16.8) | 2097 (21.1) | 1672 (16.9) | ||
| South | 16,527 (65.2) | 6521 (64.7) | 6218 (62.7) | 6422 (64.7) | ||
| West | 2190 (8.6) | 1009 (10.0) | 850 (8.6) | 986 (9.9) | ||
| Other | 5 (0.0) | 2 (0.0) | 3 (0.0) | 2 (0.0) | ||
| Insurance plan type, n (%) | 0.0000 | 0.0000 | ||||
| Exclusive provider organization | 3454 (13.6) | 1567 (15.6) | 1580 (15.9) | 1545 (15.6) | ||
| Health maintenance organization | 5628 (22.2) | 1584 (15.7) | 1820 (18.3) | 1570 (15.8) | ||
| Point of service | 14128 (55.7) | 6114 (60.7) | 5531 (55.7) | 6000 (60.5) | ||
| Other | 2153 (8.5) | 815 (8.1) | 994 (10.0) | 810 (8.2) | ||
| Index prescription, mean (SD) | ||||||
| Dose of index LT4 prescription (mcg) | 99.3 (43.9) | 102.5 (43.2) | 0.0000 | 102.3 (45.3) | 102.2 (43.1) | 0.9052 |
| Copayment for index LT4 Prescription ($) | 19.3 (13.0) | 9.5 (5.4) | 0.0000 | 21.3 (13.5) | 9.4 (5.3) | 0.0000 |
| Pre-period general health and specialist visit | ||||||
| CCI, mean (SD) | 0.4 (0.9) | 0.4 (1.0) | 0.0000 | 0.5 (1.0) | 0.4 (1.0) | 0.0714 |
| Visited endocrinologist, n (%) | 5656 (22.3) | 1591 (15.8) | 0.0000 | 1257 (12.7) | 1581 (15.9) | 0.0000 |
| Pre-period TSH and diagnoses, n (%) | ||||||
| TSH out of range | 5304 (20.9) | 2326 (23.08) | 0.4216 | 2271 (22.9) | 2278 (23.0) | 0.6676 |
| Chronic kidney disease | 121 (0.5) | 79 (0.8) | 0.0005 | 50 (0.5) | 78 (0.8) | 0.0130 |
| Depression | 1841 (7.3) | 835 (8.3) | 0.0010 | 832 (8.4) | 825 (8.3) | 0.8574 |
| Fatigue | 3515 (13.9) | 1437 (14.3) | 0.3306 | 1440 (14.5) | 1411 (14.2) | 0.5573 |
| Heart failure | 197 (0.8) | 84 (0.8) | 0.5877 | 105 (1.1) | 80 (0.8) | 0.0648 |
| Hyperlipidemia | 8423 (33.2) | 4042 (40.1) | 0.0000 | 4000 (40.3) | 3940 (39.7) | 0.3847 |
| Hypertension | 5960 (23.5) | 3000 (29.8) | 0.0000 | 2859 (28.8) | 2922 (29.4) | 0.3250 |
| Obesity | 840 (3.3) | 416 (4.1) | 0.0002 | 351 (3.5) | 407 (4.1) | 0.0381 |
Differences in means examined using t tests. Differences in categorical variables examined using chi-square tests. Propensity score matching controlled for the age, sex, region of residence, type of insurance coverage, and pre-period Charlson Comorbidity Index (CCI) score of the patient and whether the patient had a pre-period visit to an endocrinologist
LT4 levothyroxine, TSH thyroid-stimulating hormone, SD standard deviation