Table 3.
Summary of methodological characteristics of nested case—control studies.
| [Blouin et al. 2008] | [Cotte et al. 2008] | [Meijer et al. 2008] | [Rabenda et al. 2008] | [Weycker et al. 2007] | |
|---|---|---|---|---|---|
| Treatment | ALD, RSD | ALD, RSD, ETD, RAL, SR | ALD, RSD, ETD | ALD | ALD, RSD, CCT, HT, RAL |
| Evaluated drug class separately | NA | No | NA | NA | No |
| Baseline (lookback) period | 2 years | NP | 1 year | 3 months | 6 months |
| Period of covariate identificationa | 1) Baseline: 1 year for all study covariates (prior fx 2 years) 2) Follow-up: comorbidities | 1) Baseline 2) Follow-up: comorbidities, comedications and supplements in year prior to fx | 1) Baseline 2) Follow-up: Use of non-OP comedications | Baseline only | 1) Baseline 2) Follow-up: Age at fx date |
| New users (drug) | Yes (all OP drugs) | Yes (all OP drugs) | Yes (any BP) | Yes (Any BP or RAL) | Yes (all OP drugs) |
| Allowed switching | No censored switchers | Yes | NP | No excluded switchers | No excluded switchers |
| > 1 Rx needed | No | No | 1 + in two years before outcome | No | No |
| Cases — start of fracture identification | Fx at least 1 year after initiation | Fx 90 days after initiation | Fx 3 months after initiation | First fx after initiation | Fx 90 days after initiation |
| Matching of controls | |||||
| Age | Yes (+/-1yr) | Yes | No | Yes | Yes (+/-3yr) |
| Sex | Yes | Yes | Yes | Yes | Yes |
| Treatment | Yes | No | Yes | Yes | Yes |
| Index Date | Unclear | Yes | Unclear | Yes | Yes |
| Duration of Follow-up | Yes | Yes | Yes | Yes | Yes |
| Minimum confounders for adjustment in model | |||||
| Age | No (matched) | No (matched) | Yes | No (matched) | Yes |
| Prior fracture | Yes | Yes | Yes | No | Yes |
| Comorbidity Score | Yesb | No | No | No | No |
| Immeasurable time | Assumed 100% compliance | NP | NP | NP | Assumed 100% compliance |
| Compliance measure | PDC | MPR | PDC | PDC | MPR |
| How compliance quantified (1 = Primary 2 = Secondary) | 1) ≥ 80% 2) < 50% vs. ≥ 50%, <90% vs. ≥ 90% | 1) <20%, 20-<40%, 40-<60%, 60-<80%, ≥ 80% 2) Used ROCs to generate threshold | PDC ≥ 80% | PDC 1) 1 year PDC ≥ 80% 2) Continuous 0–100% | MPR <30%, 30–69%, 70–89%, ≥ 90% |
ALD, alendronate; BP, bisphosphonates; CCT, calcitonin; ETD, etidronate; Fx, fracture; GCC, glucocorticoids; HT, hormone therapy; IBD, ibandronate; MPR, medication possession ratio; NA, not applicable; NP, data not provided; OP, osteoporosis; PDC, proportion of days covered; RAL, raloxifene, RSD, risedronate; Rx, prescription; SR, strontium ranelate; Unclear, not explicitly stated in the manuscript, however plausible based on the text.
Covariates identified based on 1) ‘baseline’ — data collected during pretreatment index (lookback) period; or 2) ‘follow-up’ — data collected after treatment index date or as time varying.
Confounder considered — however, it is unclear what was included in the final adjusted analysis.