Characteristics of study cohort before and after matching
| Covariates | Before matching | After matching | ||||
| Concomitant n=2296 | Opioid only n=45 824 | P value | Concomitant n=1810 | Opioid only n=9050 | P value | |
| Age (years) | <0.01 | 0.79 | ||||
| 65–74 | 1200 (52.3) | 18 691 (40.8) | 805 (44.5) | 4103 (45.3) | ||
| 75–84 | 836 (36.4) | 19 377 (42.3) | 758 (41.9) | 3724 (41.1) | ||
| ≥85 | 260 (11.3) | 7756 (16.9) | 247 (13.6) | 1223 (13.5) | ||
| Females | 1579 (68.8) | 29 412 (64.2) | <0.01 | 1212 (67.0) | 6197 (68.5) | 0.69 |
| Race | <0.01 | 0.68 | ||||
| White | 1936 (84.3) | 37 759 (82.4) | 1490 (82.3) | 7506 (82.9) | ||
| Black | 155 (6.8) | 4350 (9.5) | 151 (8.3) | 753 (8.3) | ||
| Hispanic | 96 (4.2) | 1715 (3.7) | 84 (4.6) | 397 (4.4) | ||
| Asian | 109 (4.7) | 2000 (4.4) | 85 (4.7) | 394 (4.4) | ||
| Comorbidities | ||||||
| Respiratory events* | 568 (24.7) | 17 511 (38.2) | <0.01 | 525 (29.0) | 2596 (28.7) | 0.88 |
| Diabetes | 329 (14.3) | 10 514 (22.9) | <0.01 | 317 (17.5) | 1538 (17.0) | 0.59 |
| Heart failure | 196 (8.5) | 6049 (13.2) | <0.01 | 180 (9.9) | 924 (10.2) | 0.10 |
| Ischaemic heart disease | 367 (16.0) | 11 327 (24.7) | <0.01 | 342 (18.9) | 1686 (18.6) | 0.94 |
| Acute myocardial infarction | 19 (0.8) | 564 (1.2) | 0.08 | 16 (0.9) | 91 (1.0) | 0.63 |
| Stroke | 73 (3.2) | 2414 (5.3) | <0.01 | 70 (3.9) | 360 (4.0) | 0.78 |
| Hypertension | 752 (32.8) | 23 846 (52.0) | <0.01 | 696 (38.5) | 3546 (39.2) | 0.73 |
| Hyperlipidaemia | 632 (27.5) | 20 712 (45.2) | <0.01 | 591 (32.7) | 2940 (32.5) | 0.79 |
| Peripheral vascular disease | 202 (8.8) | 6075 (13.3) | <0.01 | 183 (10.1) | 944 (10.4) | 0.68 |
| Chronic kidney disease | 204 (8.9) | 5247 (11.5) | <0.01 | 184 (10.2) | 892 (9.9) | 0.69 |
| Pain† | 382 (16.6) | 10 123 (22.1) | <0.01 | 348 (19.2) | 1765 (19.5) | 0.50 |
| Musculoskeletal disease‡ | 422 (18.4) | 12 439 (27.1) | <0.01 | 395 (21.8) | 1979 (21.9) | 0.99 |
| Osteoporosis | 148 (6.4) | 4902 (10.7) | <0.01 | 139 (7.7) | 738 (8.2) | 0.93 |
| Mental disorders§ | 299 (13.0) | 5198 (11.3) | 0.01 | 237 (13.1) | 1163 (12.9) | 0.89 |
| Dementia | 64 (2.8) | 1943 (4.2) | <0.01 | 62 (3.4) | 287 (3.2) | 0.58 |
| Medication use | ||||||
| Antibiotics | 368 (16.0) | 7270 (15.9) | 0.84 | 277 (15.3) | 1403 (15.5) | 0.83 |
| Anticholinergic | 218 (9.5) | 7016 (15.3) | <0.01 | 210 (11.6) | 1004 (11.1) | 0.53 |
| Beta-agonists | 544 (23.7) | 14 214 (31.0) | <0.01 | 496 (27.4) | 2455 (27.1) | 0.81 |
| Inhaled corticoids | 544 (23.7) | 13 207 (28.8) | <0.01 | 473 (26.1) | 2357 (26.0) | 0.56 |
| Combined corticoids | 267 (11.6) | 7419 (16.2) | <0.01 | 250 (13.8) | 1228 (13.6) | 0.78 |
| Oral corticoids | 557 (24.3) | 11 733 (25.6) | <0.01 | 450 (24.9) | 2271 (25.1) | 0.93 |
| Theophylline | 34 (1.5) | 653 (1.4) | 0.19 | 31 (1.7) | 142 (1.6) | 0.30 |
| Oxygen supplement | 355 (15.5) | 5947 (13.0) | 0.15 | 256 (14.1) | 1284 (14.2) | 0.84 |
| Cumulative opioid MED (mg)¶ | <0.01 | 0.85 | ||||
| <150 | 44 (1.9) | 9160 (20.0) | 43 (2.4) | 219 (2.4) | ||
| 150–350 | 211 (9.2) | 13 772 (30.1) | 211 (11.7) | 1031 (11.4) | ||
| 350–900 | 494 (21.5) | 10 788 (23.5) | 493 (27.2) | 2485 (27.5) | ||
| 900–2250 | 592 (25.8) | 6795 (14.8) | 547 (30.2) | 2764 (30.5) | ||
| >2250 | 955 (41.6) | 5309 (11.6) | 516 (28.5) | 2551 (28.2) | ||
| Opioid total days supplied | <0.01 | 0.97 | ||||
| 1–10 | 192 (8.4) | 20 594 (44.9) | 191 (10.6) | 965 (10.7) | ||
| 11–30 | 439 (19.1) | 11 429 (24.9) | 439 (24.3) | 2197 (24.3) | ||
| 30–60 | 387 (16.9) | 5494 (12.0) | 379 (20.9) | 1893 (20.9) | ||
| 62–90 | 283 (12.3) | 2263 (4.9) | 221 (12.2) | 1041 (11.5) | ||
| >90 | 995 (43.3) | 6044 (13.2) | 580 (32.0) | 2954 (32.6) | ||
*COPD exacerbation and respiratory distress.
†Chronic pain, fibromyalgia and migraine.
‡Arthropathy, arthritis, lupus and rheumatoid arthritis.
§Depression, anxiety, bipolar and schizophrenia.
¶Morphine equivalent dose.
COPD, chronic obstructive pulmonary disease; MED, morphine equivalent dose.