Module C: the coverage study
Exploration notebook, module C: existing outputs only, no new analysis
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Coverage was associated with an estimated 12.2 additional prescriptions per 1,000 enrollees per quarter (95% CI 8.4 to 16.0), comparing covering with never-covering states.
Coverage and timing
| State | Delivery system | Prior authorization | BMI threshold | Step therapy |
|---|---|---|---|---|
| Mississippi | FFS | Y | >=30; BMI 27-29.9 with >=1 weight-related comorbidity | none stated in the criteria; only one anti-obesity agent co… |
| North Carolina | FFS | Y | >=30; BMI >=27 with >=1 weight-related comorbidity | Y for non-preferred agents: trial of a preferred agent (or … |
| Pennsylvania | FFS | Y | >=30 (adults) | Y for non-preferred obesity agents: history of therapeutic … |
| Michigan | FFS | Y | GLP-1 weight-loss agents: BMI classified as morbidly obese … | Y (10/01/2026 criteria): GLP-1s are non-preferred; trial an… |
| Rhode Island | FFS | Y for some products (EOHHS memo: 'some medications may requ… | not found in sourced documents | not found in sourced documents |
| Massachusetts | FFS | Y | >=30; or >=27 with a listed weight-related comorbidity | Y: inadequate response to, adverse reaction to, or contrain… |
| South Carolina | MCO (managed care program); FFS not stated | Y | >=30; BMI 30-34 needs >=1 very high-risk factor or >=2 othe… | not found in sourced documents |
| California | FFS | not found in sourced documents for the covered period (Zepb… | not found in sourced documents (the 2026 FAQ says no BMI ra… | not found in sourced documents |
| New Hampshire | FFS | Y (the PDL notes additional prior approval for the weight m… | not found in sourced documents | Y: trial and failure of 2 preferred products (orlistat, phe… |
| Utah | FFS | Y | >=30 (adults) | not found in sourced documents |
| Minnesota | FFS | Y | >=30 with no risk factors (age 18+) | none stated; documentation of a reduced-calorie diet or die… |
| Wisconsin | FFS | Y | >=30 (age 18+) | none stated; the member must have participated in a weight … |
| Virginia | FFS | Y (service authorization) | 2022 form: >=30 (>=27 with two or more risk factors); form … | Y (form effective 2026-07-01): tried and failed one non-GLP… |
| Kansas | FFS | Y | >=30 (adults); 'high-cost' agents (Table 4, includes Saxend… | Y: the preferred PDL drug is required unless the patient me… |
| Delaware | FFS | Y (the 2026 PDL: all obesity treatment agents require prior… | not found in sourced documents | Y: two preferred products are required before a non-preferr… |
| Missouri | FFS | Y (may be transparent: a billable ICD-10 obesity code on th… | >=30 (adults) | Y: preferred agents (Zepbound, Foundayo) first; Wegovy is n… |
| Tennessee | FFS | Y (interim PA criteria from 2025-08-01; Wegovy and Zepbound… | >=30 (adults) | none for the preferred agents (Wegovy, Zepbound); Y for non… |
Estimates
| estimate_type | att | se | ci_low | ci_high | method | fmi |
|---|---|---|---|---|---|---|
| Overall ATT (simple aggregation), Callaway-Sant'Anna | 12.189 | 1.947 | 8.374 | 16.004 | did multiplier bootstrap, state clusters, 999 draws; Rubin'… | 0 |
| Overall ATT (group aggregation: average of cohort ATTs), Ca… | 11.376 | 2.366 | 6.738 | 16.013 | same | 0 |
| TWFE Sun-Abraham post-period average | 9.331 | 0.561 | 8.233 | 10.430 | fixest, state-clustered; Rubin's rules over 20 imputations | 0 |
| TWFE Sun-Abraham post-period average, wild cluster bootstrap | 9.331 | NA | 4.507 | 14.155 | fwildclusterboot, Webb weights, 9,999 draws, by state; mean… | NA |
| Placebo in time: coverage 4 quarters earlier (post-launch w… | 0.383 | 0.237 | -0.081 | 0.847 | att_gt, never-treated controls, 8 treated states with cohor… | 0 |
| Secondary outcome, overall ATT (simple): Saxenda | 0.184 | 0.264 | -0.334 | 0.701 | same as the primary | 0 |
| Secondary outcome, overall ATT (simple): diabetes GLP-1 (sp… | -0.760 | 1.774 | -4.238 | 2.718 | same as the primary | 0 |
| event_time | att | se | ci_low | ci_high | band_low | band_high | fmi | treated_states | cohorts | fewer_than_3_states |
|---|---|---|---|---|---|---|---|---|---|---|
| -8 | -0.6794989 | 0.3934617 | -1.4506698 | 0.0916719 | -7.7112701 | 6.3522722 | 0.0000269 | 6 | 6 | FALSE |
| -7 | -0.5258108 | 0.3152378 | -1.1436656 | 0.0920439 | -6.1595993 | 5.1079776 | 0.0000357 | 8 | 7 | FALSE |
| -6 | -0.5167052 | 0.3008585 | -1.1063769 | 0.0729666 | -5.8935121 | 4.8601018 | 0.0000267 | 8 | 7 | FALSE |
| -5 | -0.4667323 | 0.2821808 | -1.0197965 | 0.0863318 | -5.5097400 | 4.5762753 | 0.0000215 | 8 | 7 | FALSE |
| -4 | -0.3828385 | 0.2868193 | -0.9449940 | 0.1793170 | -5.5087438 | 4.7430668 | 0.0000470 | 8 | 7 | FALSE |
| -3 | -0.0266327 | 0.0337458 | -0.0927732 | 0.0395078 | -0.6297216 | 0.5764563 | 0.0027340 | 9 | 8 | FALSE |
| -2 | 0.0417251 | 0.0546460 | -0.0653791 | 0.1488293 | -0.9348836 | 1.0183338 | 0.0011668 | 9 | 8 | FALSE |
| -1 | 0.0000000 | NA | NA | NA | NA | NA | NA | 10 | 9 | FALSE |
| 0 | 1.2558250 | 0.4094215 | 0.4533736 | 2.0582763 | -6.0611714 | 8.5728213 | 0.0000273 | 10 | 9 | FALSE |
| 1 | 3.7214361 | 1.4308087 | 0.9171026 | 6.5257696 | -21.8493328 | 29.2922050 | 0.0000023 | 9 | 8 | FALSE |
| 2 | 6.2637039 | 2.4538921 | 1.4541639 | 11.0732440 | -37.5911499 | 50.1185577 | 0.0000012 | 9 | 8 | FALSE |
| 3 | 8.4905104 | 3.6709740 | 1.2955337 | 15.6854871 | -57.1154831 | 74.0965039 | 0.0000004 | 9 | 8 | FALSE |
| estimator | estimate | se | ci_low | ci_high |
|---|---|---|---|---|
| (a) Callaway-Sant'Anna simple aggregation, all post cells | 12.189 | 1.947 | 8.374 | 16.004 |
| (b) CS dynamic, mean of e = 0..12, equal weights | 13.715 | 2.865 | 8.099 | 19.331 |
| (c) CS dynamic, mean of e = 0..12, Sun-Abraham cell weights… | 11.076 | 2.459 | 6.257 | 15.895 |
| (c2) CS group-time estimates, e = 0..12, weighted like the … | 11.076 | NA | NA | NA |
| (d) TWFE Sun-Abraham post-period average | 9.331 | 0.561 | 8.233 | 10.430 |
Withdrawals (preliminary)
| unit | group | obesity_wz | all_drugs | normalised |
|---|---|---|---|---|
| CA | Withdrawing / lapsed | -0.7573 | -0.2604 | -0.6718 |
| PA | Withdrawing / lapsed | -0.9551 | -0.5100 | -0.9083 |
| SC | Withdrawing / lapsed | -0.6173 | 0.0118 | -0.6218 |
| NC | Withdrawing / lapsed | 3.8707 | -0.0016 | 3.8785 |
| NH | Withdrawing / lapsed | -0.8822 | -0.1915 | -0.8543 |
| KS | Continuously covered | -0.3775 | -0.5257 | 0.3126 |
| MI | Continuously covered | -0.2674 | -0.0273 | -0.2468 |
| MS | Continuously covered | 0.0572 | -0.2798 | 0.4679 |
Part of the project report; every number comes from analysis/outputs/key_numbers.csv. Public aggregate data; no company affiliation or endorsement.