Table III.
Methotrexate (MTX) doses among cases and controls and dose-response analysis
| Cases (n = 623) | Controls (n = 6,230) | OR (95% CI) | p-value | |
|---|---|---|---|---|
| MTX exposure, n (%) | ||||
| Never | 463 (74) | 4,860 (78) | 1 [Reference] | |
| Ever | 160 (26) | 1,370 (22) | 1.23 (1.02–1.49) | 0.034 |
| MTX dose intervals (g), n (%) | ||||
| None | 463 (74) | 4,860 (78) | 1 [Reference] | |
| (0, 2.5) | 90 (14) | 866 (14) | 1.10 (0.86–1.39) | 0.45 |
| (2.5, 5) | 41 (7) | 307 (5) | 1.40 (1.00–1.97) | 0.049 |
| (5, 7.5) | 21 (3) | 145 (2) | 1.54 (0.96–2.47) | 0.073 |
| >7.5 | 8 (1) | 52 (1) | 1.64 (0.77–3.49) | 0.20 |
| Per oral MTX dose (g)a, median (range)* | 1.75 (0.08,8.73) n = 147 | 1.50 (0.08,13.58) n = 1,316 | 1.06 (1.00–1.12)d | 0.047 |
| Subcutaneous MTX dose (g)b, median (range)* | 1.02 (0.04,10.63) n = 33 | 0.90 (0.01,12.15) n = 238 | 1.09 (0.97–1.23)d | 0.14 |
| Total MTX dose (g)c, median (range)* | 2.06 (0.04,10.63) n = 160 | 1.73 (0.01,13.58) n = 1,370 | 1.06 (1.01–1.12)d | 0.014 |
Filled prescriptions of MTX was available in the period July 2005 to 2016. The accumulated MTX doses was calculated up to the index date, which was in the period 2010 to 2016.
The oral MTX doses are the accumulated doses of oral MTX among cases and controls. For this specific odds ratio (OR), conditional logistic regression controlling for the subcutaneous dose was used.
The subcutaneous MTX doses are the accumulated doses of subcutaneous MTX among cases and controls. For this specific OR, conditional logistic regression controlling for the oral dose was used.
Conditional logistic regression was used with only the total dose as the independent variable.
ORs indicating the increase in risk of cutaneous squamous cell carcinoma per 1 g increment in MTX dose.
Dose among exposed.
95% CI: 95% confidence interval.