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Impact of Positive Airway Pressure Among Obstructive Sleep Apnea Patients
Qian Cai, MS, MSPH; Hiangkiat Tan, MS, BPharm; and Joseph Singer, MD

Impact of Positive Airway Pressure Among Obstructive Sleep Apnea Patients

Qian Cai, MS, MSPH; Hiangkiat Tan, MS, BPharm; and Joseph Singer, MD
The hospitalization risks and costs of positive airway pressure were evaluated among patients with obstructive sleep apnea in a real-world setting.
Objectives: To evaluate the clinical and economic impact of positive airway pressure (PAP) among patients with obstructive sleep apnea (OSA).


Study Design: Retrospective claims-based analysis of OSA patients diagnosed with polysomnography (PSG) between January 1, 2005, and April 30, 2008.


Methods: Patients were required to have 2 or more claims for OSA diagnosis within 1 year after their first PSG test, and a minimum of 12 months’ baseline and 24 months’ follow-up continuous health plan enrollment. Patients with pulmonary disease or PAP use before the first PSG test were excluded. Outcomes included all-cause and sleep apnea–related hospitalization and healthcare costs. Multivariable analyses were performed to adjust for baseline characteristics.


Results: Of the 15,424 patients identified, 90.7% used PAP and 9.3% did not. The PAP group had lower all-cause (19.0% vs 24.2%, P <.001) and sleep apnea–related (8.0% vs 11.3%, P <.001) hospitalization rates than the non-PAP group during the follow-up period. After adjusting for baseline characteristics, patients in the PAP group were less likely to have an all-cause (odds ratio [OR] 0.70; 95% confidence interval [CI] 0.61-0.80]) or sleep apnea–related (OR 0.69; 95% CI 0.58-0.83) hospitalization than non-PAP patients. PAP users on average incurred 10% lower all-cause costs than non-PAP patients ($705 per member per month vs $786 per member per month, P <.001) in multivariable analysis.


Conclusions: Among OSA patients in real-world practice, PAP users had significantly lower hospitalization risks and all-cause healthcare costs.


(Am J Manag Care. 2012;18(6):e225-e233)
This study demonstrated that patients with obstructive sleep apnea (OSA) who initiated positive airway pressure (PAP) had clinically significant lower hospitalization risk and lower all-cause healthcare costs than patients who did not use PAP.

  •  To our knowledge, this is the first study that used a large administrative claims database to compare economic outcomes of OSA patients who used PAP with those of OSA patients who did not.

  •  With data from real-world practice, findings can be used by health plans in educating patients and physicians about screening and diagnostic testing for OSA, and for selecting appropriate treatment of OSA.
Obstructive sleep apnea (OSA) is a common breathing disorder characterized by the recurrence of partial or complete collapse of the soft palate and associated soft tissues of the upper airway during sleep.1 This results in oxygen deprivation from poor gas exchange, which leads to arousals from sleep and overall sleep fragmentation.2 Available population-based studies indicate that the prevalence of OSA ranges from 3% to 7% in adult men and 2% to 5% among adult women.3,4 Among middle-aged adults, the prevalence of OSA is 26% for men and 9% for women.5 The prevalence of OSA has been reported to increase with age at a steady rate, especially among men.3,6

The most common symptoms of OSA include daytime sleepiness, loud snoring, interrupted breathing, and choking-related awakenings.2,7,8 Recent epidemiologic studies have demonstrated that OSA is associated with cardiovascular disease,9 heart failure, coronary artery disease, cerebrovascular disease, diabetes mellitus,2,10,11 and hypertension.12-14 Additionally, OSA has also been identified as a primary independent risk factor in the development of hypertension15 and heart failure.16 Despite known health risks, current literature suggests that more than 80% of patients with moderate to severe OSA have not been clinically diagnosed.11,17

Two commonly accepted tests for OSA are in-laboratory polysomnography (PSG) and in-home testing facilitated by portable monitors.7 For more than 2 decades now, PSG has gained acceptance as the gold standard for the diagnosis of sleep-associated disordered breathing.18-21 The use of PSG is typically associated with supervised overnight laboratory testing to diagnose all cases of suspected OSA. In addition to the PSG diagnostic test, a variety of monitoring devices have been used to measure breathing disturbances during sleep in studies,22 and for the titration of continuous positive air pressure (CPAP) in the treatment of OSA.23 Commercial health plans and the Centers for Medicare & Medicaid Services include tests associated with breathing-affected sleep in their benefits package.24

Among the available treatments for OSA, positive air pressure(PAP) devices have become the acknowledged gold standard for treating patients with moderate to severe OSA.2,7,25 The most common form of PAP, CPAP, works through the application of positive pressure to the upper airway at a constant level to keep the pharyngeal airway open during sleep. The bilevel PAP, which provides 2 levels of pressure to maintain set airway pressures, is also commonly used to treat OSA, especially for patients who are intolerant of or unresponsive to initial fixed-pressure CPAP. The Agency for Healthcare Research and Quality in the United States has not developed guidelines for the treatment of OSA, but does promote those introduced by the United Kingdom’s National Institute of Health and Clinical Excellence, which recommended CPAP and bilevel PAP as technology-based treatment options for adults diagnosed with moderate or severe OSA.25 The Adult OSA Task Force of the American Academy of Sleep Medicine has also recommended the use of CPAP for the treatment of moderate to severe OSA patients and bilevel PAP in the management of OSA in CPAP-intolerant patients.7

Costs attributable to the diagnosis and treatment of moderate to severe OSA are estimated at $2 billion to $10 billion per year. This reflects only a small proportion of the overall estimated economic burden of the disease, which ranges from $65 billion to $165 billion after accounting for absenteeism, loss of productivity, and workplace and traffic accidents.8 Given the increased morbidity associated with OSA, it is plausible that undiagnosed or untreated OSA may have an economic burden on the healthcare system. Kapur et al reported that patients diagnosed with OSA have $1336 higher annual medical costs in the year prior to their diagnosis compared with matched controls, which could well represent an estimate of the medical costs of untreated OSA.26 A Canadian study compared OSA patients with matched controls over a 10-year prediagnosis period and found that patients with OSA used about twice as many healthcare services during the prediagnosis period as patients in the control group, adding to the evidence that patients with OSA are heavy users of healthcare services.27

Available evidence shows that CPAP and bilevel PAP therapy are safe.7,28 The economic impact of treating OSA patients with PAP, however, has not been well evaluated and documented. One small Swedish study, which compared hospitalizations before and after CPAP initiation among 88 OSA patients within a 2-year period, found that CPAP therapy reduced hospital admissions among OSA patients and resulted in reduced consumption of healthcare resources.29 To date, no study has used a large population sample to assess the clinical and economic effects of PAP in realworld practice. This study was designed to evaluate the impact of PAP on hospitalization risks and healthcare costs among patients with PSG-diagnosed OSA using a large health insurance administrative claims database.

METHODS

Study Design


This was a retrospective cohort study using patient-level administrative claims data from the HealthCore Integrated Research Database, which consists of 12 regional commercial health insurance plans spread across the northeastern, southeastern, mid-Atlantic, Midwestern, and western regions of the United States. At the time this study was conducted, the HealthCore Integrated Research Database included medical claims, pharmacy claims, eligibility files, and laboratory test results data for approximately 43 million health plan enrollees. All data used in this observational study were deidentified and accessed using protocols compliant with the regulations of the Health Insurance Portability and Accountability Act of 1996. Patient confidentiality was preserved and the anonymity of all patient data was safeguarded throughout the study.

Inclusion and Exclusion Criteria

Patients between 18 and 64 years old with a medical claim for a PSG diagnostic test (Current Procedural Terminology [CPT] codes of 95806-95811) between January 1, 2005, and April 30, 2008, were identified. Patients were required to have 2 or more claims with a diagnosis code for OSA (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code of 327.23) within 1 year after their first PSG test date. Patients older than 65 years were excluded from this study to avoid confounding due to potential dual coverage, with Medicare as an additional insurer. To make sure that patients were newly treated with PAP, subjects who had claims indicating the use of PAP (Healthcare Common Procedure Coding System [HCPCS] codes of E0601, E0470, or E0471), PAP-related supplies (HCPCS codes of A7027- A7039, A7045, or A7046), or PAP management (CPT code of 94660) prior to the first PSG test date were excluded. To avoid confounding by other primary respiratory conditions, patients with asthma (ICD-9 493.xx), chronic bronchitis (ICD-9 491.xx), emphysema (ICD-9 492.xx), extrinsic allergic alveolitis (ICD-9 495.xx), cystic fibrosis (ICD-9 277.0x), other alveolar and parietoalveolar pneumonopathy (ICD-9 516.xx), other sleep apnea (ICD-9 327.2x except 327.23), and pneumoconioses and other lung disease due to external agents (ICD-9 500.xx-506.xx) were also excluded due to the potential contradiction and compromise for the evaluation of the effectiveness of PAP use among OSA patients (Appendix).

The index date for patients using PAP (PAP group) was defined as the date of the first medical claim for PAP use. For patients not using PAP (non-PAP group), an index date was randomly assigned through Monte Carlo simulation based on the length of time between the PSG test and the initiation of PAP for corresponding PAP users. After simulation, a minimum of 36 months (12 months before the index date and 24 months after the index date) of continuous eligibility was required for both groups to ensure an adequate follow-up period for economic and clinical evaluation.

Study Measures

The main outcomes of interest were all-cause and sleep apnea– related hospitalization and direct costs over a 24-month postindex period. The all-cause hospitalization referred to inpatient admission with any cause of diagnosis, whereas the sleep apnea–related hospitalization referred to any inpatient admission with a sleep apnea diagnosis (ICD-9 327.23, 780.53, 780.57, or 780.51). Hospitalization risk was defined as the probability of having 1 or more hospitalizations during the follow-up period. Annualized hospital admission rates were used to assess the number of admissions per 1000 persons per year. The total all-cause costs were defined as the sum of medical and pharmacy costs associated with any condition from the claims data. Sleep apnea–related costs referred to costs associated with the treatment of sleep apnea incurred from inpatient, emergency department, and outpatient services, which were a subset of the all-cause costs. Costs were calculated on a per member per month (PMPM) basis, using the allowable amount reimbursed by health plans.

Baseline or the preindex period was defined as the 12 months prior to the index date (not including the index date) whereas the follow-up or postindex period was defined as 24 months after the index date (including the index date). Patients’ characteristics including age, sex, health plan type, and geographic region were compared between the 2 cohorts. Patients’ comorbid conditions were measured using the Deyo-Charlson Comorbidity Index (DCI) and specific sleep apnea–related comorbid conditions during the 12-month baseline period. The DCI consists of 19 diagnoses identified by ICD-9-CM codes, with a weight from 1 to 6 identified for each diagnosis.30 The final score consists of a sum of weighted values for the present comorbidities, and higher scores indicate greater comorbidity burden. In addition, baseline allcause and sleep apnea–related hospitalization and direct costs were captured.

Statistical Analysis

 
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