Data for these analyses were obtained from the Truven Health Analytics MarketScan® Database, an administrative claims database. The database includes health insurance claims from large employers and health plans across the USA, and contains de-identified fully adjudicated pharmacy claims (e.g., outpatient prescriptions) and medical claims (e.g., inpatient and outpatient services) submitted for payment by providers, healthcare facilities, and pharmacies. Claims include information on each physician visit, medical procedure, hospitalization, drugs dispensed, dates of service/prescription dispensing, number of days of medication supplied, and tests performed. Member enrollment and benefit information and limited patient and provider information are also available.
This was a retrospective cohort study, which used one-sample, pre–post analyses to compare differences in HCU before and after etanercept initiation. The full study period was 2009–2014, and patient identification was between 2010 and 2013. The index date was the date of the first etanercept claim during the patient identification period. Study outcomes were evaluated for the 12-month period before (baseline period) and the 12-month period after (follow-up period) etanercept initiation.
To be eligible, patients had to have initiated etanercept during the identification period, had at least one inpatient or outpatient claim with an RA diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 714.0) in the primary position during the 12 months prior to index date or on the index date, and 12 months of continuous enrollment in the health plan (with a pharmacy benefit) before and after the index date (total enrollment of 24 months). Patients were excluded for any of the following: claim for any bDMARD in the 12-month pre-index baseline period, age less than 18 years at start of baseline or over 64 years at index date, or a claim for psoriasis, psoriatic arthritis, ankylosing spondylitis, or juvenile idiopathic arthritis (other indications for etanercept) in the baseline period.
Etanercept utilization and HCU were assessed. The proportion of days covered (PDC) was the primary measure of etanercept utilization, and was calculated as the quotient of the number of days covered (using days supplied) during follow-up divided by 365 days. Assessment of HCU included office visits (for disease evaluation and management), inpatient admissions, emergency department visits, outpatient services (i.e., hospital outpatient clinic visits), RA-related procedures of total joint arthroplasty, joint reconstruction, and soft tissue repairs, RA-related pharmacotherapy, diagnostic tests, and select comorbidities. RA-related HCU was determined by a diagnosis of RA as the primary diagnosis on the claim for inpatient admissions and emergency department visits and by a diagnosis of RA in any position on outpatient services. Outpatient services were further stratified by office visits, outpatient hospital services, and laboratory visits. RA-related pharmacotherapies included TNFi medications and other bDMARDs (during follow-up only), and nonbiologic DMARDs (nbDMARDs), oral nonsteroidal anti-inflammatory drugs (NSAIDs), oral corticosteroids, and oral opioid analgesics. Diagnostic tests included complete blood cell counts, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, anti-cyclic citrullinated peptide antibodies, anti-mutated citrullinated vimentin antibodies, and a multi-biomarker disease activity test. HCU was identified using health insurance claims data by ICD-9-CM codes for diagnoses, Current Procedural Terminology (CPT) codes for procedures, National Drug Code (NDC) for medication dispensings, and Healthcare Common Procedure Coding System (HCPCS) codes for infused medications. Outcomes were evaluated in the 12-month baseline and post-index periods.
Data transformations and statistical analyses were conducted using SAS version 9.4 (SAS Institute, Cary, NC, USA). Descriptive statistics were generated for hospitalization (overall and RA-related), outpatient visits (overall and RA-related), and RA-related surgical procedures in the baseline and follow-up periods. For continuous outcome variables, the mean difference between baseline and follow-up values was estimated. For dichotomous outcome variables, the difference in proportions was estimated. The difference was calculated as the value during follow-up minus the value during baseline.
Statistical testing was performed using McNemar’s test for dichotomous variables, paired t test for continuous variables, and Wilcoxon signed rank test for nonparametric continuous variables. Post-index HCU was also evaluated for three categories of PDC: 0–39%, 40–79%, and 80–100% in secondary analyses. For these analyses, F test and Chi square test were used for continuous variables and categorical variables, respectively, and rank sum test was used for nonparametric continuous variables. The relative risk (RR) with 95% confidence intervals (CI) of any emergency department visit (overall or RA-related) or any inpatient admission (overall or RA-related) was calculated as the post-index rate divided by the baseline rate, and 95% CIs were based on a naïve approach that assumed comparison groups were independent.
An analysis of HCU stratified by baseline use (yes/no) of nbDMARDs was conducted. A sensitivity analysis using a 90-day “skip period,” in which the 12-month follow-up period was started 90 days after index date, was conducted as a reduction in utilization with etanercept would have been underestimated if utilization temporarily increased shortly after treatment initiation.
Compliance with Ethics Guidelines
This article does not contain any new studies with human or animal subjects performed by any of the authors.