Table 2.
Association between Tramadol Initiation and Risk of Incident Myocardial Infarction within Six-month Follow-up Comparing with Initiation of Naproxen among Patients with Osteoarthritis
| Tramadol | Naproxen | |
|---|---|---|
| Primary analysis | ||
| Participants (n) | 33,024 | 33,024 |
| Incident myocardial infarction (n) | 77 | 46 |
| Mean follow-up (year) | 0.49 | 0.49 |
| Rate (1000 person-years)* | 4.8 | 2.8 |
| RD (1000 person-years, 95% CI) | 1.9 (0.6, 3.3) | 0.0 (reference) |
| HR (95% CI) | 1.68 (1.16, 2.41) | 1.00 (reference) |
| “As-treated” approach** | ||
| Participants (n) | 33,024 | 33,024 |
| Incident myocardial infarction (n) | 40 | 23 |
| Mean follow-up (year) | 0.25 | 0.24 |
| Rate (1000 person-years) | 4.9 | 2.9 |
| RD (1000 person-years, 95% CI) | 2.0 (0.1, 3.9) | 0.0 (reference) |
| HR (95% CI) | 1.66 (1.00, 2.76) | 1.00 (reference) |
| Incident OA patients | ||
| Participants (n) | 20,159 | 20,159 |
| Incident myocardial infarction (n) | 35 | 20 |
| Mean follow-up (year) | 0.49 | 0.49 |
| Rate (1000 person-years) | 3.6 | 2.0 |
| RD (1000 person-years, 95% CI) | 1.5 (0.1, 3.0) | 0.0 (reference) |
| HR (95% CI) | 1.75 (1.01, 3.03) | 1.00 (reference) |
| Missing data imputation | ||
| HR (95% CI) | 1.57 (1.13, 2.17) | 1.00 (reference) |
| Conventional covariate adjustment approach | ||
| HR (95% CI) | 1.59 (1.19, 2.12) | 1.00 (reference) |
RD, rate difference; HR, hazard ratio; n, number; 95% CI, 95% confidence interval; OA, osteoarthritis.
*
Number (rate) of competing event (i.e., death) in tramadol and naproxen cohort was 457 (28.3/1000 person-years) and 207 (12.8/1000 person-years), respectively.
**
82% and 85% participants discontinued or switched their initiated treatment in tramadol and naproxen cohort, respectively.