Chest
Volume 146, Issue 1, July 2014, Pages 142-151
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Original Research
Genetic and Developmental Disorders
Pulmonary Medication Adherence and Health-care Use in Cystic Fibrosis

https://doi.org/10.1378/chest.13-1926Get rights and content

BACKGROUND

Poor treatment adherence is common in cystic fibrosis (CF) and may lead to worse health outcomes and greater health-care use. This study evaluated associations of adherence to pulmonary medications, age, health-care use, and cost among patients with CF.

METHODS

Patients with CF aged ≥ 6 years were identified in a national commercial claims database. A 12-month medication possession ratio (MPR) was computed for each pulmonary medication and then averaged for a composite MPR (CMPR) for each patient. The CMPR was categorized as low (< 0.50), moderate (0.50-0.80), or high (≥ 0.80). Annual health-care use and costs were measured during the first and second year and compared across adherence categories by multivariable modeling.

RESULTS

Mean CMPR for the sample (N = 3,287) was 48% ± 31%. Age was inversely related to CMPR. In the concurrent year, more CF-related hospitalizations were observed among patients with low (event rate ratio [ERR], 1.35; 95% CI, 1.15-1.57) and moderate (ERR, 1.25; 95% CI, 1.05-1.48) vs high adherence; similar associations were observed for all-cause hospitalizations and CF-related and all-cause acute care use (hospitalizations + ED) in the concurrent and subsequent year. Rates of CF-related and all-cause outpatient visits did not differ by adherence. Low and moderate adherence predicted higher concurrent health-care costs by $14,211 ($5,557-$24,371) and $8,493 (−$1,691 to $19,709), respectively, compared with high adherence.

CONCLUSIONS

Worse adherence to pulmonary medications was associated with higher acute health-care use in a national, privately insured cohort of patients with CF. Addressing adherence may reduce avoidable health-care use.

Section snippets

Data Source and Sample Selection

The Thomson Reuters MarketScan Commercial Claims and Encounters Database (January 2005 to June 2011) includes medical and drug data for active employees and their dependents with primary coverage through employer-sponsored private health insurance throughout the United States.18 The MarketScan claims database offers the largest claims capture of physician office visits; hospital stays; retail, mail-order, and specialty pharmacies; and carve-out care. The database undergoes extensive validity

Patient Characteristics

The study sample included 3,287 patients with CF (Table 1). Mean age was 22.8 ± 13.0 years, and female patients comprised 49% of the sample (Table 2). The demographic characteristics of the present sample were comparable to the general CF population as reported in the Cystic Fibrosis Registry1; however, the present sample included more adults (age ≥ 18 years, 56% vs 48%) and more patients with Pseudomonas aeruginosa infection (63.0% vs 51%). A subgroup of 1,420 patients had continuous

Discussion

This retrospective analysis used administrative claims data from a large, nationwide database to evaluate the relationship between overall long-term pulmonary medication adherence and demographic variables, health-care use, and health-care costs among patients with CF. About one-half of the sampled patients filled less than one-half of their medications, which is consistent with adherence rates seen in other chronic illnesses.19 Adherence over a 1-year period, categorized as low (CMPR < 0.50),

Conclusions

Achieving and maintaining adherence to long-term pulmonary therapy is critically important to the effective management of CF. This study found that rates of adherence to long-term CF pulmonary medications, using 12-month CMPRs, were significant predictors of subsequent health-care use and costs in a national sample of patients with CF. Adherence to long-term pulmonary medications was quite low (< 50%) and differed systematically across age and sex. Additional research is needed to understand

Acknowledgments

Author contributions: J. S. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. A. L. Q., J. Z., M. M., P. A. C., J. S., and K. A. R. contributed to the study conception and design; A. L. Q., J. Z., M. M., P. A. C., J. S., and K. A. R. contributed to data interpretation; M. M., P. A. C., J. S., and Y. Y. contributed to data analysis; A. L. Q., M. M., P. A. C., and K. A. R. contributed to the writing of the

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Parts of this study have been reported in abstract form at the 26th Annual North American Cystic Fibrosis Conference, October 11-13, 2012, Orlando, FL.

FUNDING/SUPPORT: This study was supported by the Novartis Pharmaceuticals Corp, which manufactures inhaled tobramycin.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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