Table 1.
Proportion of antidepressants prescribed for off-label indications and level of evidence, by drug class
| Drug class (No of prescriptions) | Off-label indication | Level of evidence for off-label indications | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No | Percentage* (95% CI†) | Strong evidence for prescribed drug‡ | No strong evidence for prescribed drug but strong evidence for another drug in same class¶ | No strong evidence for prescribed drug and all other drugs in same class | ||||||
| No | Percentage§ (95% CI†) | No | Percentage§ (95% CI†) | No | Percentage§ (95% CI†) | |||||
| SSRI (n=45 608) | 9960 | 21.8 (19.0 to 25.0) | 473 | 4.7 (2.7 to 7.2) | 9160 | 92.0 (89.2 to 94.4) | 327 | 3.3 (2.0 to 4.8) | ||
| SNRI (n=25 235) | 1539 | 6.1 (4.8 to 7.5) | 169 | 11.0 (4.6 to 18.4) | 544 | 35.4 (25.0 to 46.7) | 826 | 53.7 (40.6 to 66.6) | ||
| TCA (n=11 645) | 9480 | 81.4 (77.3 to 85.5) | 4335 | 45.7 (37.8 to 54.0) | 2682 | 28.3 (20.5 to 36.6) | 2463 | 26.0 (21.2 to 31.1) | ||
| Other** (n=24 362) | 10 340 | 42.4 (37.1 to 47.7) | 0 | 0.0 (0.0 to 0.0) | NA | NA | 10 340 | 100.0 (100.0 to 100.0) | ||
| All classes (n=106 850) | 31 319 | 29.3 (26.6 to 32.3) | 4977 | 15.9 (13.0 to 19.3) | 12 386 | 39.6 (35.7 to 43.2) | 13 956 | 44.6 (40.2 to 49.0) | ||
SSRI=selective serotonin reuptake inhibitors; SNRI=serotonin-norepinephrine reuptake inhibitors; TCA=tricyclic antidepressants; NA=not assessed for drugs in this category because they were not considered as part of the same class.
*Calculated using the total number of prescriptions in the class as the denominator.
†Calculated by a cluster bootstrap approach26 to account for non-independence of prescriptions from the same physician and for the same patient. Reported 95% confidence intervals correspond to values at the 2.5th and 97.5th percentiles of the distribution of respective estimates across 1000 bootstrap re-samples.
‡Based on evaluations from DRUGDEX compendium in three dimensions: efficacy, strength of recommendation, and strength of evidence. Prescriptions for an off-label indication were classified as having strong evidence for a prescribed drug if evidence showed that the drug was effective or favoured efficacy for the indication, the drug was recommended for all or most patients with the indication, and at least one randomised controlled trial was included among the studies used to evaluate the drug’s efficacy for the indication.
§Calculated using the number of prescriptions in the class that were written for an off-label indication as the denominator.
¶Off-label prescriptions where the prescribed drug did not have strong evidence for the indication, but another drug in the class was either on-label or off-label with strong evidence for the indication based on evaluations from the DRUGDEX compendium.
**Includes trazodone, bupropion, and mirtazapine.