[Table 1 here]
LTOT definitions (Figure 2, Table 2) : Approximately two-thirds of the 126 studies used two or more criteria to define LTOT (80 studies). Definitions were generally based on one measure of opioid duration, such as days of use or supply (84 studies, 67%), episode length (27 studies, 21%) or prescription fills within a specified time period (11 studies, 9%). Additional criteria included the number of fills (56 studies, 44%), continuous use (34 studies, 27%) or other criteria (16 studies, 13%). Only seven studies (6%) considered opioid dosage to derive LTOT definitions.
Overlapping opioid prescriptions were addressed in 22 studies (17%). Twelve studies carried forward supplies occurring before the prior prescription ended, of which seven studies carried forward supplies for a specific number of overlapping days (e.g., < 10 days or 20% of overlapping). [45-47] The remaining 10 studies considered overlapping prescriptions as concurrent use.
LTOT definitions were based on previous publications (79 studies, 63%), clinical judgment (21 studies, 17%), or empirical data (4 studies, 3%) and only 12 studies tested more than one definition (10%).