Factors associated with potential drug–drug interactions detected by the Medscape drug checker according to multiple linear regression model
| Variable | B | P value | 95% Cl |
| Medscape total interactions | |||
| Age | −0.049 | 0.003 | −0.081 to −0.017 |
| Red blood cells | −0.678 | 0.031 | −1.294 to −0.063 |
| Erythrocyte sedimentation rate | −0.038 | 0.013 | −0.069 to −0.008 |
| C-reactive protein | 0.030 | 0.034 | 0.002 to 0.057 |
| Diagnosis | −0.642 | 0.005 | −1.087 to −0.196 |
| Number of pharmacological/therapeutic subgroups (second level of ATC classification) | 1.577 | 0.000 | 1.327 to 1.827 |
| Antiepileptic drugs | 1.204 | 0.003 | 0.912 to 1.996 |
| Anticholinergics | 1.121 | 0.005 | 0.348 to 1.893 |
| Antihypertensives | 2.102 | 0.005 | 0.623 to 3.582 |
| Statins | 1.671 | 0.001 | 0.693 to 2.665 |
| Antibiotic drugs | 1.114 | 0.006 | 0.325 to 1.903 |
| Antacids | 2.831 | 0.000 | 1.847 to 3.814 |
| Laxatives | 1.264 | 0.013 | 0.272 to 2.256 |
| Tetanus vaccine | 2.226 | 0.002 | 0.841 to 3.611 |
| Vitamins | 1.751 | 0.000 | 0.974 to 2.528 |
| Number of diagnoses | −0.611 | 0.012 | −1.086 to −0.135 |
| Urinary tract infection | −1.858 | 0.000 | −2.803 to −0.912 |
| Hypertension | −1.548 | 0.044 | −3.055 to −0.042 |
| Number of associated comorbidities | 0.916 | 0.002 | 0.335 to 1.497 |
| Heart attack | 2.153 | 0.001 | 0.907 to 3.400 |
| Liver disease | 1.966 | 0.011 | 0.450 to 3.483 |
| Number of interactions in which the route of the drug increased the manifestation of the interaction | 0.722 | 0.000 | 0.357 to 1.087 |
| Number of interactions in which the dose of the drug increased the manifestation of the interaction R2=0.555; F (p)=21.471 (0.000*) | 0.767 | 0.027 | 0.085 to 1.449 |
| Contraindicated | |||
| Length of hospitalisation (days) | 0.002 | 0.022 | 0.000 to 0.003 |
| Antibiotic drugs | 0.041 | 0.025 | 0.005 to 0.077 |
| Antidiabetic drugs | −0.137 | 0.000 | −0.203 to −0.072 |
| Charlson Comorbidity Index (CCI) | −0.026 | 0.001 | −0.041 to −0.010 |
| Smoker | 0.046 | 0.010 | 0.011 to 0.082 |
| Tumour | −0.162 | 0.002 | −0.263 to −0.061 |
| Number of interactions in which the dose of the drug increased the manifestation of the interaction R2=0.101; F (p)=6.689 (0.000)* | 0.090 | 0.000 | 0.051 to 0.129 |
| Serious – use alternative | |||
| Gamma-glutamyl transferase (GGT) | 0.004 | 0.008 | 0.001 to 0.008 |
| Number of pharmacological/therapeutic subgroups (second level of ATC classification) | 0.095 | 0.000 | 0.052 to 0.138 |
| Dopaminergic drugs | −1.347 | 0.000 | 1.816 to −0.878 |
| Antihypertensives | 0.241 | 0.029 | 0.025 to 0.458 |
| Diuretics | −0.243 | 0.036 | −0.469 to −0.016 |
| Anticoagulants | −0.375 | 0.006 | 0.643 to −0.107 |
| Antacids | 0.258 | 0.032 | 0.023 to 0.494 |
| Vitamins | 0.270 | 0.003 | 0.091 to 0.449 |
| Urinary tract infection | −0.329 | 0.001 | −0.529 to −0.129 |
| Number of associated comorbidities | 0.608 | 0.000 | 0.353 to 0.863 |
| Heart attack | 0.608 | 0.001 | 0.236 to 0.981 |
| Cerebrovascular accident | 0.851 | 0.000 | 0.395 to 1.306 |
| Dementia | 0.782 | 0.001 | 0.337 to 1.226 |
| Chronic obstructive pulmonary disease (COPD) | 0.749 | 0.000 | 0.364 to 1.134 |
| Rheumatic diseases | 0.653 | 0.002 | 0.247 to 1.058 |
| Peptic ulcer disease | 0.554 | 0.007 | 0.155 to 0.953 |
| Liver disease | 1.111 | 0.000 | 0.673 to 1.550 |
| Diabetes mellitus | 0.745 | 0.000 | 0.412 to 1.078 |
| Renal failure | 0.867 | 0.000 | 0.464 to 1.270 |
| Tumour | 0.448 | 0.046 | 0.008 to 0.889 |
| Number of interactions in which the dose of the drug increased the manifestation of the interaction R2=0.310; F (p)=10.139 (0.000)* | 0.373 | 0.000 | 0.216 to 0.530 |
*Statistically significant.
ATC, Anatomical Therapeutic Chemical; B, unstandardised coefficient; p, statistical significance.