Table 5.
Multivariate logistic regression analysis of factors associated with potential drug–drug interactions (DDI)
| No. of patients (%) | Univariate analysis | Multivariate analysis | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No potential DDI | Potential DDI | Unadjusted odds ratio | 95% C.I. | p value | Adjusted odds ratio | 95% C.I. | p value | |||
| Lower | Upper | Lower | Upper | |||||||
| Age | ||||||||||
| 18–64 | 191 (65.6%) | 100 (34.4%) | Reference | |||||||
| >=65 | 92 (36.4%) | 161 (63.6%) | 3.342 | 2.350 | 4.754 | <.001 | 1.222 | .758 | 1.972 | .409 |
| Gender | ||||||||||
| Male | 122 (56.7%) | 93 (43.3%) | Reference | |||||||
| Female | 161 (48.9%) | 168 (51.1%) | 1.369 | .969 | 1.934 | .075 | 1.543 | .987 | 2.412 | .057 |
| Ethnicity | ||||||||||
| Indo-trinidadian | 109 (51.9%) | 101 (48.1%) | Reference | |||||||
| Afro-trinidadian | 118 (51.3%) | 112 (48.7%) | 1.024 | .704 | 1.489 | .900 | ||||
| Mixed | 54 (53.5%) | 47 (46.5%) | .939 | .584 | 1.511 | .796 | ||||
| Other | 2 (66.7%) | 1 (33.3%) | .540 | .048 | 6.042 | .617 | ||||
| Education | ||||||||||
| None | 7 (30.4%) | 16 (69.6%) | Reference | |||||||
| Primary | 82 (42.3%) | 112 (57.7%) | .598 | .235 | 1.519 | .279 | .869 | .269 | 2.814 | .815 |
| Secondary | 153 (60.5%) | 100 (39.5%) | .286 | .114 | .720 | .008 | .717 | .224 | 2.298 | .575 |
| Vocational | 10 (58.8%) | 7 (41.2%) | .306 | .082 | 1.137 | .077 | .886 | .176 | 4.452 | .883 |
| University | 30 (54.5%) | 25 (45.5%) | .365 | .130 | 1.026 | .056 | 1.329 | .362 | 4.881 | .668 |
| Not recorded | 1 (50%) | 1 (50%) | .438 | .024 | 8.036 | .578 | .281 | .004 | 20.309 | .561 |
| Medical formulation | ||||||||||
| OTC | 102 (47.7%) | 112 (52.3%) | 1.334 | .945 | 1.883 | .102 | .790 | .485 | 1.288 | .345 |
| Herbal | 28 (56%) | 22 (44%) | .838 | .467 | 1.506 | .555 | .710 | .320 | 1.577 | .401 |
| Combination | 83 (58.5%) | 59 (41.5%) | .704 | .478 | 1.036 | .075 | .533 | .309 | .919 | .024 |
| Polypharmacy | 59 (24.2%) | 185 (75.8%) | 9.242 | 6.245 | 13.676 | <.001 | 6.392 | 3.691 | 11.069 | .000 |
| Chronic illness | ||||||||||
| DM | 45 (27.8%) | 117 (72.2%) | 4.297 | 2.877 | 6.419 | <.001 | 1.442 | .842 | 2.469 | .182 |
| HTN | 47 (21.3%) | 174 (78.7%) | 10.043 | 6.696 | 15.061 | <.001 | 3.972 | 2.437 | 6.473 | <.001 |
| IHD | 8 (11.8%) | 60 (88.2%) | 10.261 | 4.800 | 21.937 | <.001 | 3.633 | 1.477 | 8.938 | .005 |
| Psych | 6 (18.2%) | 27 (81.8%) | 5.327 | 2.162 | 13.123 | <.001 | 2.514 | .851 | 7.429 | .095 |
| Asthma | 35 (71.4%) | 14 (28.6%) | .402 | .211 | .765 | <.001 | .350 | .152 | .807 | .014 |
Each ‘medical formulation’ and ‘chronic illness’ was treated as an independent covariate in the equation; for each of these variables, patients without the variable were used as the reference
OTC over the counter, DM diabetes mellitus, HTN hypertension, IHD ischaemic heart disease