Table 2.
Baseline demographic variables for the propensity-matched patients receiving hydroxychloroquine compared with those not receiving hydroxychloroquine
| Patients receiving hydroxychloroquine (n=10 703) | Patients not receiving hydroxychloroquine (n=21 406) | Standardised mean difference in odds ratio (95% CI) | p value | ||
|---|---|---|---|---|---|
| Rheumatological condition | |||||
| Rheumatoid arthritis | 7193 (67·2%) | 15 049 (70·3%) | −0·0805 (−0·107 to 0·520) | <0·0001 | |
| Systemic lupus erythematosus | 2642 (24·7%) | 4475 (20·9%) | 0·119 (0·088 to 0·149) | <0·0001 | |
| Polymyositis | 87 (0·8%) | 317 (1·5%) | −0·334 (−0·466 to −0·203) | <0·0001 | |
| Polyarthritis | 208 (1·9%) | 400 (1·9%) | 0·002 (−0·071 to 0·115) | 0·64 | |
| Sjögren's syndrome | 398 (3·7%) | 406 (1·9%) | 0·382 (0·304 to 0·459) | <0·0001 | |
| Behcet's syndrome | 4 (<0·1%) | 2 (<0·1%) | 0·764 (−0·171 to 1·70) | 0·10 | |
| Jaccoud's syndrome | 1 (<0·1%) | 3 (<0·1%) | −0·224 (−1·470 to 1·020) | 0·72 | |
| Connective tissue disease | 422 (3·9%) | 666 (3·1%) | 0·135 (0·067 to 0·204) | <0·0001 | |
| CREST syndrome | 9 (<0·1%) | 7 (<0·1%) | 0·521 (−0·024 to 1·07) | 0·060 | |
| Felty's syndrome | 12 (0·1%) | 34 (0·2%) | −0·192 (−0·555 to 0·171) | 0·29 | |
| Inflammatory polyarthritis | 346 (3·2%) | 605 (2·8%) | 0·076 (0·002 to 0·150) | 0·044 | |
| Systemic sclerosis | 75 (0·7%) | 148 (0·7%) | 0·008 (−0·146 to 0·161) | 0·92 | |
| Still's disease | 4 (<0·1%) | 11 (<0·1%) | −0·176 (−0·807 to 0·455) | 0·58 | |
| Palindromic rheumatism | 76 (0·7%) | 155 (0·7%) | −0·011 (−0·163 to 0·141) | 0·89 | |
| Polyarthralgia rheumatica | 246 (2·3%) | 574 (2·7%) | −0·087 (−0·170 to −0·004) | 0·038 | |
| Demographics | |||||
| Age, years | 64·8 (12·9) | 65·4 (13·3) | −0·047 (−0·702 to −0·238) | <0·0001 | |
| Sex | .. | .. | −0·063 (−0·093 to 0·033) | <0·0001 | |
| Men | 8029 (75·0%) | 16 502 (77·1%) | .. | .. | |
| Women | 2674 (25·0%) | 4904 (22·9%) | .. | .. | |
| Rural residence | 4126 (38·5%) | 8252 (38·5%) | .. | 1·0 | |
| Race | .. | .. | 0·042 (0·015 to 0·070) | 0·0023 | |
| White | 7292 (68·1%) | 14 221 (66·4%) | .. | .. | |
| Black | 2107 (19·7%) | 4464 (20·9%) | .. | .. | |
| Hispanic | 542 (5·1%) | 1045 (4·9%) | .. | .. | |
| Native American | 148 (1·4%) | 259 (1·2%) | .. | .. | |
| Asian or Pacific Islander | 172 (1·6%) | 343 (1·6%) | .. | .. | |
| Unknown | 442 (4·1%) | 1074 (5·0%) | .. | .. | |
| Body-mass index, kg/m2 | 30·0 (6·2) | 29·7 (6·2) | 0·044 (0·020 to 0·067) | 0·0005 | |
| Any tobacco use | 1175 (11·0%) | 2297 (10·7%) | 0·014 (−0·027 to 0·055) | 0·50 | |
| Rheumatological prescriptions | |||||
| Leflunomide | 654 (6·1%) | 1225 (5·7%) | 0·038 (−0·016 to 0·092) | 0·16 | |
| Methotrexate | 2214 (20·7%) | 4489 (21·0%) | −0·010 (−0·041 to 0·022) | 0·55 | |
| Sulfasalazine | 947 (8·8%) | 1378 (6·4%) | 0·190 (0·142 to 0·237) | <0·0001 | |
| Any other oral csDMARD* | 3388 (31·7%) | 6499 (30·4%) | 0·033 (0·006 to 0·061) | 0·018 | |
| Chronic steroid use | 1001 (9·4%) | 1707 (8·0%) | 0·096 (0·051 to 0·141) | <0·0001 | |
| Prednisone equivalent >20 mg per day | 51 (0·5%) | 89 (0·4%) | 0·076 (−0·115 to 0·266) | 0·44 | |
| Any biological therapy | 1548 (14·5%) | 3228 (15·1%) | −0·027 (−0·063 to 0·009) | 0·14 | |
| Other csDMARD* plus biologic | 760 (7·1%) | 1683 (7·9%) | −0·061 (−0·110 to −0·012) | 0·015 | |
| Methotrexate plus biologic | 473 (4·4%) | 1104 (5·2%) | −0·089 (−0·150 to −0·029) | 0·0036 | |
| Methotrexate plus other csDMARD* plus biologic | 53 (0·5%) | 92 (0·4%) | 0·078 (−0·108 to 0·265) | 0·41 | |
| Other prescriptions of interest | |||||
| Angiotensin II receptor blocker | 943 (8·8%) | 1804 (8·4%) | 0·027 (−0·019 to 0·072) | 0·25 | |
| Angiotensin-converting enzyme 2 inhibitor | 1551 (14·5%) | 2992 (14·0%) | 0·023 (−0·013 to 0·060) | 0·21 | |
| Vitamin D | 2565 (24·0%) | 4679 (21·9%) | 0·066 (0·036 to 0·096) | <0·0001 | |
| Vitamin C | 186 (1·7%) | 326 (1·5%) | 0·074 (−0·026 to 0·174) | 0·15 | |
| Zinc | 14 (0·1%) | 39 (0·2%) | −0·183 (−0·520 to 0·154) | 0·28 | |
| Comorbidities | |||||
| Respiratory | 2342 (21·9%) | 4429 (20·7%) | 0·039 (0·008 to 0·070) | 0·014 | |
| Renal or urinary | 2636 (24·6%) | 4996 (23·3%) | 0·039 (0·009 to 0·069) | 0·011 | |
| Cardiovascular | 4402 (41·1%) | 8895 (41·6%) | −0·010 (−0·036 to 0·016) | 0·47 | |
| Gastrointestinal | 2487 (23·2%) | 4576 (21·4%) | 0·059 (0·029 to 0·090) | 0·0002 | |
| Hepatobiliary | 337 (3·1%) | 651 (3·0%) | 0·020 (−0·054 to 0·093) | 0·60 | |
| Neurological | 3232 (30·2%) | 6046 (28·2%) | 0·052 (0·024 to 0·080) | 0·0003 | |
| Dermatological | 1706 (15·9%) | 3311 (15·5%) | 0·020 (−0·015 to 0·055) | 0·27 | |
| Metabolic or endocrine | 4547 (42·5%) | 9521 (44·5%) | −0·045 (−0·071 to −0·019) | 0·0007 | |
| Haematological | 1423 (13·3%) | 2651 (12·4%) | 0·045 (0·007 to 0·083) | 0·021 | |
| Psychiatric | 3059 (28·6%) | 5994 (28·0%) | 0·016 (−0·013 to 0·044) | 0·28 | |
| Neoplastic | 1379 (12·9%) | 2561 (12·0%) | 0·047 (0·008 to 0·085) | 0·018 | |
| Laboratory abnormalities | |||||
| Elevated alkaline phosphatase | 142 (1·3%) | 336 (1·6%) | −0·094 (−0·203 to 0·015) | 0·087 | |
| Elevated alanine aminotransferase | 199 (1·9%) | 451 (2·1%) | −0·070 (−0·163 to 0·022) | 0·13 | |
| Elevated aspartate aminotransferase | 459 (4·3%) | 978 (4·6%) | −0·036 (−0·099 to 0·026) | 0·25 | |
| Elevated lactate dehydrogenase | 408 (3·8%) | 641 (3·0%) | 0·138 (0·068 to 0·207) | <0·0001 | |
| Low haemoglobin | 4790 (44·8%) | 9290 (43·4%) | 0·030 (0·004 to 0·561) | 0·021 | |
| Thrombocytopenia | 585 (5·5%) | 1218 (5·7%) | −0·024 (−0·079 to 0·325) | 0·41 | |
| Leukocytosis | 558 (5·2%) | 1267 (5·9%) | −0·074 (−0·130 to −0·018) | 0·010 | |
| Leucopenia | 172 (1·6%) | 291 (1·4%) | 0·094 (−0·011 to 0·198) | 0·082 | |
| Elevated urea nitrogen | 1098 (10·3%) | 2353 (11·0%) | −0·043 (−0·084 to −0·001) | 0·045 | |
| Elevated creatinine | 720 (6·7%) | 1497 (7·0%) | −0·023 (−0·074 to 0·028) | 0·37 | |
| Elevated erythrocyte sedimentation rate | 1926 (18·0%) | 3501 (16·4%) | 0·064 (0·030 to 0·097) | 0·0002 | |
| Elevated C-reactive protein >10 μg/mL | 691 (6·5%) | 1303 (6·1%) | 0·035 (−0·018 to 0·087) | 0·20 | |
Data are n (%) or mean (SD) unless otherwise stated. csDMARD=conventional synthetic disease-modifying antirheumatic drug.
*
csDMARDs include hydroxychloroquine, methotrexate, lefunomide, and sulfasalazine; other csDMARD refers to agents other than hydroxychloroquine.