Risk factor | No. (%) | Risk of hospital admission for allopurinol-associated severe cutaneous adverse reactions per 1000 patients (95% CI) | Relative risk (95% CI) | |||
---|---|---|---|---|---|---|
Allopurinol initiators | Hospital admissions for severe cutaneous adverse reactions | Age- and sex-adjusted | Primary multivariable* | Secondary multivariable† | ||
All | 130 325 (100) | 109 | 0.84 (0.69–1.01) | – | – | – |
Sex | ||||||
Male | 93 127 (71.5) | 49 (45.0) | 0.53 (0.39–0.70) | 1.0 | 1.0 | 1.0 |
Female | 37 198 (28.5) | 60 (55.0) | 1.61 (1.23–2.08) | 2.45 (1.67–3.61) | 2.48 (1.67–3.70) | 2.45 (1.65–3.65) |
Age, yr | ||||||
Continuous, 1-year age increase | – | – | – | – | 1.02 (1.00–1.04) | – |
< 60 | 53 895 (41.4) | 23 (21.1) | 0.43 (0.27–0.64) | 1.0 | – | 1.0 |
60–70 | 34 572 (26.5) | 21 (19.3) | 0.61 (0.38–0.93) | 1.76 (1.37–2.25) | – | 2.24 (1.33–3.78) |
≥70 | 41 858 (32.1) | 65 (59.6) | 1.55 (1.20–1.98) | 3.09 (1.89–5.06) | – | 5.04 (1.77–14.30) |
Region‡ | ||||||
Continuous, per 1% Asian increase | – | – | – | – | 1.03 (1.02–1.04) | – |
Richmond | 5584 (4.3) | 8 (7.3) | 1.43 (0.62–2.82) | 4.66 (2.66–8.15) | – | 4.67 (2.65–8.25) |
Vancouver and Fraser North | 34 408 (26.4) | 54 (49.5) | 1.57 (1.18–2.05) | 2.79 (1.92–4.05) | – | 2.80 (1.92–4.08) |
North Shore and Fraser South | 26 685 (20.5) | 15 (13.8) | 0.56 (0.31–0.93) | 1.67 (1.39–2.01) | – | 1.67 (1.38–2.02) |
Remainder | 63 648 (48.8) | 32 (29.4) | 0.50 (0.34–0.71) | 1.0 | – | 1.0 |
Heart disease | ||||||
Yes | 28 176 (21.6) | 43 (39.4) | 1.53 (1.10–2.06) | 1.84 (1.23–2.76) | 1.60 (1.04–2.44) | 1.55 (1.01–2.37) |
No | 102 149 (78.4) | 66 (60.6) | 0.65 (0.50–0.82) | 1.0 | 1.0 | 1.0 |
Chronic kidney disease | ||||||
Yes | 15 874 (12.2) | 26 (23.9) | 1.64 (1.07–2.40) | 1.70 (1.08–2.67) | 1.86 (1.16–2.99) | 1.88 (1.17–3.02) |
No | 114 451 (87.8) | 83 (76.1) | 0.73 (0.58–0.90) | 1.0 | 1.0 | 1.0 |
Diabetes | ||||||
Yes | 32 870 (25.2) | 36 (33.0) | 1.10 (0.77–1.52) | 1.12 (0.75–1.68) | 0.96 (0.63–1.46) | 0.95 (0.62–1.45) |
No | 97 455 (74.8) | 73 (67.0) | 0.75 (0.59–0.94) | 1.0 | 1.0 | 1.0 |
Gout | ||||||
Yes | 79 764 (61.2) | 57 (52.3) | 0.71 (0.54–0.93) | 0.80 (0.55–1.16) | 0.80 (0.54–1.16) | 0.80 (0.55–1.17) |
No | 50 561 (38.8) | 52 (47.7) | 1.03 (0.77–1.35) | 1.0 | 1.0 | 1.0 |
Diuretic use | ||||||
Yes | 42 539 (32.6) | 55 (50.5) | 1.29 (0.97–1.68) | 1.32 (0.88–1.98) | 1.27 (0.84–1.94) | 1.26 (0.83–1.92) |
No | 87 786 (67.4) | 54 (49.5) | 0.62 (0.46–0.80) | 1.0 | 1.0 | 1.0 |
Initial allopurinol dosage | ||||||
> 100 mg/d | 82 853 (63.6) | 86 (78.9) | 1.04 (0.83–1.28) | 2.53 (1.59–4.02) | 2.79 (1.75–4.45) | 2.78 (1.75–4.43) |
≤100 mg/d | 47 472 (36.4) | 23 (21.1) | 0.48 (0.31–0.73) | 1.0 | 1.0 | 1.0 |
Note: CI = confidence interval
↵* Adjusted for sex, age (continuous), % Asian (continuous), heart disease, chronic kidney disease, diabetes, gout, diuretic use and initial allopurinol dosage.
↵† Adjusted for sex, age, region, heart disease, chronic kidney disease, diabetes, gout, diuretic use and initial allopurinol dosage.
↵‡ Regions are grouped by proportion of Asian people in the population according to data from the 2016 Canadian Census (Appendix 1, available at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.190339/-/DC1) and are used here as a surrogate for Asian race, which has the highest prevalence of the HLA-B*5801 polymorphism.