Clinical and economic outcomes in an observational study of COPD maintenance therapies: multivariable regression versus propensity score matching

Melissa H Roberts1, Anand A Dalal21Lovelace Clinic Foundation, (Lovelace Respiratory Research Institute at the time of the study), Albuquerque, NM, 2US Health Outcomes, GlaxoSmithKline, Durham, NC, USAPurpose: To investigate equivalency of results from multivariable regression (MR) and propensity score matching (PSM) models, observational research methods used to mitigate bias stemming from non-randomization (and consequently unbalanced groups at baseline), using, as an example, a large study of chronic obstructive pulmonary disease (COPD) initial maintenance therapy.Methods: Patients were 32,338 health plan members, age ≥40 years, with COPD initially treated with fluticasone propionate/salmeterol combination (FSC), tiotropium (TIO), or ipratropium (IPR) alone or in combination with albuterol. Using MR and PSM methods, the proportion of patients with COPD-related health care utilization, mean costs, odds ratios (ORs), and incidence rate ratios (IRRs) for utilization events were calculated for the 12 months following therapy initiation.Results: Of 12,595 FSC, 9126 TIO, and 10,617 IPR patients meeting MR inclusion criteria, 89.1% (8135) of TIO and 80.2% (8514) of IPR patients were matched to FSC patients for the PSM analysis. Methods produced substantially similar findings for mean cost comparisons, ORs, and IRRs for most utilization events. In contrast to MR, for TIO compared to FSC, PSM did not produce statistically significant ORs for hospitalization or outpatient visit with antibiotic or significant IRRs for hospitalization or outpatient visit with oral corticosteroid. As in the MR analysis, compared to FSC, ORs and IRRs for all other utilization events, as well as mean costs, were less favorable for IPR and TIO.Conclusion: In this example of an observational study of maintenance therapy for COPD, more than 80% of the original treatment groups used in the MR analysis were matched to comparison treatment groups for the PSM analysis. While some sample size was lost in the PSM analysis, results from both methods were similar in direction and statistical significance, suggesting that MR and PSM were equivalent methods for mitigating bias.Keywords: multivariate analysis, outcomes research, propensity score, pulmonary disease, chronic obstructive, statistical bias, statistical model

The role of fluticasone propionate/salmeterol combination therapy in preventing exacerbations of COPD

Exacerbations contribute significantly to the morbidity of COPD, leading to an accelerated decline in lung function, reduced functional status, reduced health status and quality of life, poorer prognosis and increased mortality. Prevention of exacerbations is thus an important goal of COPD management. In patients with COPD, treatment with a combination of the inhaled corticosteroid fluticasone propionate (250 μg) and the long-acting β2-agonist salmeterol (50 μg) in a single inhaler (250/50 μg) is an effective therapy option that has been shown to reduce the frequency of exacerbations, to improve lung function, dyspnea and health status, and to be relatively cost-effective as a COPD maintenance therapy. Importantly, results of various studies suggest that fluticasone propionate and salmeterol have synergistic effects when administered together that improve their efficacy in controlling symptoms and reducing exacerbations. The present non-systematic review summarizes the role of fluticasone propionate/salmeterol combination therapy in the prevention of exacerbations of COPD and its related effects on lung function, survival, health status, and healthcare costs

Economic burden of chronic bronchitis in the United States: a retrospective case-control study

Christopher M Blanchette1, Melissa H Roberts1, Hans Petersen1, Anand A Dalal2, Douglas W Mapel31Division of Clinical and Outcomes Research, Lovelace Respiratory Research Institute, Kannapolis, NC, USA; 2US Health Outcomes, GlaxoSmithKline, Research Triangle Park, NC, USA; 3Lovelace Clinic Foundation, Albuquerque, NM, USABackground: Chronic bronchitis (CB) is often misdiagnosed or diagnosed at a later stage of chronic obstructive pulmonary disease (COPD). We examined how this later diagnosis may impact health care costs and utilization during the 12 months prior to and 24 months post initial CB diagnosis.Methods: This retrospective case-control analysis used claims data from a large US database from July 1, 2003 through June 30, 2007. Patients with CB aged 40 years and older were propensity matched (N = 11,674) to patients without evidence of COPD or asthma by demographics, CB diagnosis quarter/year, and comorbidities. Group differences were assessed using Student's t-test and Pearson chi-square test statistics.Results: Six months prediagnosis, CB patients had higher frequencies of any hospitalization (9.6%, 6.7%; P < 0.05), emergency department/urgent care visits (13.3%, 6.7%; P < 0.05), and prescriptions (97.3%, 94.1%; P < 0.05). Six months postdiagnosis, CB patients had 5.6 times more hospitalizations (P < 0.05) and 3.1 times more emergency department/urgent care visits (P < 0.05) compared with controls. Mean total costs (US) for CB patients 12 months prediagnosis were significantly higher than controls (months 12–7: 4212, 3826; P < 0.05; months 6–1: 5289, 4285; P < 0.05). CB patients had higher mean total costs (8919; P < 0.05) 6 months postdiagnosis. Costs remained $2429 higher for CB patients 19–24 months postdiagnosis (P < 0.05).Conclusion: Health care costs and utilization among CB patients are increased both prior to diagnosis and during the 2 years postdiagnosis. This study suggests that not accurately diagnosing CB early has a substantial impact on health care costs, and that the economic burden for CB patients remains elevated even after adjustment for comorbidities associated with COPD.Keywords: chronic bronchitis, burden, economic, chronic obstructive pulmonary diseas