To the Editor: Psoriatic disease often requires long-term therapy, but many patients face out-of-pocket treatment costs not covered by insurance. Prior studies in other chronic conditions have found that higher out-of-pocket costs may affect rates of treatment adherence, defined as the degree to which the patient takes their medication as prescribed, and treatment discontinuation, defined as the patient’s cessation of a treatment before being advised to by their provider.1,2 This study examined associations between out-of-pocket costs and treatment patterns among patients with psoriatic disease using biologic or oral systemic medications.
Patients with psoriasis and/or psoriatic arthritis were identified using the MarketScan Commercial Claims and Encounters and Medicare Supplemental databases (2018-2022) (Supplementary Table I, available via Mendeley at https://data.mendeley.com/datasets/w5tfxybj9t/1). For each patient, out-of-pocket costs were calculated over a 1-year follow-up period by adding deductible, copay, and coinsurance payments made for a study medication (Supplementary Table II, available via Mendeley at https://data.mendeley.com/datasets/w5tfxybj9t/1). Adherence was measured by the proportion of days covered (PDC), defined as the sum of the days supplied with the study medication divided by the 365 days in the follow-up period (≥0.80 classified adherence).3 Discontinuation was measured by treatment gaps, defined as the number of days since the patient exhausted their most recent prescription’s supply (≥90 days classified discontinuation).3 Medication switches were treated as discontinuations, as our goal was to assess treatment patterns specific to the initial therapy. Relative risks (RR) were derived using an established method based on predicted probabilities from logistic regression and were adjusted for patient characteristics (Table I).4
Table I.
Cohort characteristics of patients with psoriasis and/or psoriatic arthritis, stratified by out-of-pocket cost paid for a biologic or oral systemic medication over 30 days
| Out-of-pocket cost for 30-day medication supply |
|||||||
|---|---|---|---|---|---|---|---|
| <$15 (n = 5679) |
$15-99 (n = 7013) |
$100-249 (n = 1982) |
$250-499 (n = 1332) |
$500-999 (n = 1303) |
≥$1000 (n = 1975) |
Total (n = 19,284) |
|
| n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |
| Diagnosis | |||||||
| Psoriasis only | 1295 (22.8) | 2840 (40.5) | 810 (40.9) | 542 (40.7) | 556 (42.7) | 880 (44.6) | 6923 (35.9) |
| Psoriatic arthritis only | 1450 (25.5) | 1178 (16.8) | 302 (15.2) | 208 (15.6) | 195 (15.0) | 242 (12.2) | 3575 (18.5) |
| Concurrent psoriasis and psoriatic arthritis | 2934 (51.7) | 2995 (42.7) | 870 (43.9) | 582 (43.7) | 552 (42.4) | 853 (43.2) | 8786 (45.6) |
| Age, y | |||||||
| Mean (SD) | 53.6 (12.3) | 50.3 (11.6) | 49.1 (10.7) | 49.1 (10.6) | 49.3 (11.2) | 48.2 (11.0) | 50.8 (11.7) |
| Sex | |||||||
| Male | 2437 (42.9) | 3345 (47.7) | 1028 (51.9) | 713 (53.5) | 684 (52.5) | 983 (49.8) | 9190 (47.7) |
| Female | 3242 (57.1) | 3668 (52.3) | 954 (48.1) | 619 (46.5) | 619 (47.5) | 992 (50.2) | 10,094 (52.3) |
| CCI | |||||||
| Mean (SD) | 0.22 (0.67) | 0.16 (0.63) | 0.13 (0.55) | 0.14 (0.55) | 0.11 (0.47) | 0.12 (0.54) | 0.17 (0.61) |
| Census region | |||||||
| Northeast | 1002 (17.6) | 1159 (16.5) | 241 (12.2) | 164 (12.3) | 171 (13.1) | 302 (15.3) | 3039 (15.8) |
| Midwest | 1527 (26.9) | 1396 (19.9) | 391 (19.7) | 269 (20.2) | 268 (20.6) | 360 (18.2) | 4211 (21.8) |
| South | 1955 (34.4) | 2708 (38.6) | 849 (42.8) | 618 (46.4) | 596 (45.7) | 952 (48.2) | 7678 (39.8) |
| West | 627 (11.0) | 699 (10.0) | 363 (18.3) | 180 (13.5) | 183 (14.0) | 202 (10.2) | 2254 (11.7) |
| Not reported | 568 (10.0) | 1051 (15.0) | 138 (6.8) | 101 (7.6) | 85 (6.5) | 159 (8.1) | 2102 (10.9) |
| Insurance payer | |||||||
| Commercial | 4772 (84.0) | 6543 (93.3) | 1942 (98.0) | 1303 (97.8) | 1248 (95.8) | 1927 (97.6) | 17,735 (92.0) |
| Medicare | 907 (16.0) | 470 (6.7) | 40 (2.0) | 29 (2.2) | 55 (4.2) | 48 (2.4) | 1549 (8.0) |
| Insurance plan | |||||||
| Comprehensive | 460 (8.1) | 292 (4.2) | 38 (1.9) | 41 (3.1) | 22 (1.7) | 17 (0.9) | 870 (4.5) |
| EPO | 41 (0.7) | 63 (0.9) | 36 (1.8) | 8 (0.6) | 8 (0.6) | 20 (1.0) | 176 (0.9) |
| HMO | 914 (16.1) | 1431 (20.4) | 234 (11.8) | 123 (9.2) | 86 (6.6) | 138 (7.0) | 2926 (15.2) |
| Non-capitated POS | 304 (5.4) | 423 (6.0) | 153 (7.7) | 105 (7.9) | 71 (5.4) | 65 (3.3) | 1121 (5.8) |
| PPO | 2887 (50.8) | 3638 (51.9) | 1062 (53.6) | 550 (41.3) | 552 (42.4) | 925 (46.8) | 9614 (49.9) |
| Capitated or partially capitated POS | 15 (0.3) | 31 (0.4) | 4 (0.2) | 4 (0.3) | 0 (0.0) | 1 (0.1) | 55 (0.3) |
| CDHP | 533 (9.4) | 770 (11.0) | 309 (15.6) | 172 (12.9) | 230 (17.6) | 335 (17.0) | 2349 (12.2) |
| HDHP | 439 (7.7) | 271 (3.9) | 113 (5.7) | 313 (23.5) | 313 (24.0) | 449 (22.7) | 1898 (9.8) |
| Not reported | 86 (1.5) | 94 (1.3) | 33 (1.7) | 16 (1.2) | 21 (1.6) | 25 (1.3) | 275 (1.4) |
| Overall treatment class | |||||||
| Biologic | 1354 (23.8) | 5738 (81.8) | 1819 (91.8) | 1234 (92.6) | 1154 (88.6) | 1826 (92.5) | 13,125 (68.1) |
| Oral systemic | 4325 (76.2) | 1275 (18.2) | 163 (8.2) | 98 (7.4) | 149 (11.4) | 149 (7.5) | 6159 (31.9) |
CCI, Charlson Comorbidity Index; CDHP, Consumer-Driven Health Plan; EPO, Exclusive Provider Organization; HDHP, High Deductible Health Plan; HMO, Health Maintenance Organization; POS, Point-of-Service; PPO, Preferred Provider Organization; SD, standard deviation.
Among 19,284 patients, only 38.6% adhered to treatment and 54.4% discontinued treatment over 1 year (Fig 1). Compared to patients paying <$15 for a 30-day medication supply, those paying $15-99, $100-249, $250-499, and $500-999 were more likely to adhere to treatment (aRR (95% CI) = 1.23 (1.14-1.33), 1.32 (1.19-1.46), 1.77 (1.52-2.07), and 1.55 (1.36-1.77), respectively) and were less likely to discontinue treatment (0.87 (0.84-0.90), 0.79 (0.75-0.83), 0.54 (0.51-0.57), and 0.66 (0.62-0.70), respectively). In contrast, patients paying ≥$1000 were less likely to adhere to treatment (0.80 (0.74-0.86)) (Supplementary Tables III and IV, available via Mendeley at https://data.mendeley.com/datasets/w5tfxybj9t/1).
Fig 1.
Associations between out-of-pocket costs and adherence and discontinuation rates for biologic and oral systemic treatments among patients with psoriasis and/or psoriatic arthritis.
Importantly, these results should not be interpreted as paying $15-999 improves treatment patterns compared to paying <$15. Rather, our findings may reflect pharmacy benefit manager (PBM) dynamics.5 Patients paying $15-999 may be using medications positioned more favorably on formularies due to PBM rebate incentives, enabling greater treatment continuity. In contrast, patients paying <$15 may be using medications outside of PBM-preferred channels, relying on short-term assistance and coverage arrangements more vulnerable to disruption. Additionally, excessive costs may still disrupt care, as patients paying ≥$1000 were significantly less likely to adhere to treatment. Overall adherence and discontinuation rates were also only 38.6% and 54.4%, respectively, indicating that barriers to consistent medication use remain.
In this study, rates of treatment adherence and discontinuation varied significantly by out-of-pocket costs. This research provides valuable insights to guide advocacy efforts aimed at reducing treatment costs and increasing access to care for patients with psoriatic disease.
Conflicts of interest
Armstrong has served as a research investigator, scientific advisor, or speaker to AbbVie, Alumis, BMS, Galderma, Leo, UCB, J&J, Lilly, Novartis, Sun, Sanofi, Takeda, Regeneron, and Pfizer. Roberts, Jeong, Chou, Ma, Katz, Yan, Johnsen, and Nong have no conflict of interest to disclose.
Footnotes
Funding sources: This study was funded by the National Psoriasis Foundation/USA. Funders supported the research independent of the investigators and did not have influence over the content of this work.
Patient consent: Not applicable.
IRB approval status: This study was considered exempt from review by the University of California, Los Angeles Institutional Review Board because all of the data obtained by investigators were fully deidentified.
Data availability statement: The data analyzed in this study were made available through Merative MarketScan Research Databases through a contractual agreement. Restrictions apply to the availability of these data according to Merative MarketScan policies for licensed access.
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