Drug check resulta | Total | Dose reduction Yes; n (%)b | Dose reduction No; n (%) | Odds ratio (95% CI) | P valuec |
 Positive | 391 | 142 (36.32) | 249 (63.68) | 9.36 (4.25–20.65) | 0.0001 |
 Negative | 122 | 7 (5.74) | 115 (94.26) | Ref. |  |
Drug check resulta | Total | Drug disposal Yes; n (%) | Drug disposal No; n (%) | Odds ratio (95% CI) | P valuec |
 Positive | 436 | 50 (11.47) | 386 (88.53) | 1.60 (0.79–3.26) | 0.186 |
 Negative | 134 | 10 (7.46) | 124 (92.54) | Ref. |  |