Table 2.
Medication usage and frequency of potential drug–drug interactions
| Total | Age ≥65 years | Age 18–64 years | All patients | p value | |
|---|---|---|---|---|---|
| 275 | 374 | 649 | |||
| Medication usage patterns | |||||
| OTC | n (%) | 100 (36.4%) | 138 (36.9%) | 238 (36.7%) | .934 |
| Herbal | n (%) | 18 (6.5%) | 34 (9.1%) | 52 (8%) | .306 |
| Combine | n (%) | 50 (18.2%) | 94 (25.1%) | 144 (22.2%) | .036 |
| Polypharmacy | n (%) | 154 (56%) | 90 (24.1%) | 244 (37.6%) | <.001 |
| Number of potential interactions seen in each patient | <.001 | ||||
| 0 | n (%) | 92 (33.5%) | 191 (51.1%) | 283 (43.6%) | <.001 |
| 1–5 | n (%) | 53 (19.3%) | 57 (15.2%) | 110 (16.9%) | .162 |
| 6–10 | n (%) | 73 (26.5%) | 37 (9.9%) | 110 (16.9%) | <.001 |
| >10 | n (%) | 35 (12.7%) | 6 (1.6%) | 41 (6.3%) | <.001 |
| Patients on <2 drugs | n (%) | 22 (8.0%) | 83 (22.2%) | 105 (16.2%) | <.001 |
| Most severe potential interaction seen in each patient | <.001* | ||||
| Contraindication | n (%) | 6 (3.7%) | 0 (0%) | .430 | .430 |
| Potential major interaction | n (%) | 62 (38.5%) | 24 (22%) | 86 (33.0%) | .005 |
| Potential moderate interaction | n (%) | 88 (54.7%) | 66 (66%) | 154 (59%) | .070 |
| Potential minor interaction | n (%) | 5 (3.1%) | 10 (10%) | 15 (5.7%) | .020 |
| Total | n (%) | 161 (100%) | 100 (100%) | 261 (100%) | |
* Significance calculated using fisher exact test with post hoc analysis
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