Model correction of diagnostic coding-based RSV incidence for children 0-4 years in the US.

BACKGROUND: Although administrative claims data have a high degree of completeness, not all medically attended Respiratory Syncytial Virus-associated lower respiratory tract infections (RSV-LRTIs) are tested or coded for their causative agent. We sought to determine the attribution of RSV to LRTI in claims data via modeling of temporal changes in LRTI rates against surveillance data. METHODS: We estimated the weekly incidence of LRTI (inpatient, outpatient, and total) for children 0-4 years using 2011-2019 commercial insurance claims, stratified by HHS region, matched to the corresponding weekly NREVSS RSV and influenza positivity data for each region, and modelled against RSV, influenza positivity rates, and harmonic functions of time assuming negative binomial distribution. LRTI events attributable to RSV were estimated as predicted events from the full model minus predicted events with RSV positivity rate set to 0. RESULTS: Approximately 42% of predicted RSV cases were coded in claims data. Across all regions, the percentage of LRTI attributable to RSV were 15-43%, 10-31%, and 10-31% of inpatient, outpatient, and combined settings, respectively. However, when compared to coded inpatient RSV-LRTI, 9 of 10 regions had improbable corrected inpatient LRTI estimates (predicted RSV/coded RSV ratio < 1). Sensitivity analysis based on separate models for PCR and antigen-based positivity showed similar results. CONCLUSIONS: Underestimation based on coding in claims data may be addressed by NREVSS-based adjustment of claims-based RSV incidence. However, where setting-specific positivity rates is unavailable, we recommend modeling across settings to mirror NREVSS's positivity rates which are similarly aggregated, to avoid inaccurate adjustments.

RSV testing practice and positivity by patient demographics in the United States: integrated analyses of MarketScan and NREVSS databases.

BACKGROUND: RSV-incidence estimates obtained from routinely-collected healthcare data (e.g., MarketScan) are commonly adjusted for under-reporting using test positivity reported in national Surveillance Systems (NREVSS). However, NREVSS lacks detail on patient-level characteristics and the validity of applying a single positivity estimate across diverse patient groups is uncertain. We aimed to describe testing practices and test positivity across subgroups of private health insurance enrollees in the US and illustrate the possible magnitude of misclassification when using NREVSS to correct for RSV under ascertainment. METHODS: Using billing records, we determined distributions of RSV-test claims and test positivity among a national sample of private insurance enrollees. Tests were considered positive if they coincided with an RSV-diagnosis. We illustrated the influence of positivity variation across sub-populations when accounting for untested acute respiratory infections. RESULTS: Most tests were for children (age 0-4: 65.8%) and outpatient encounters (78.3%). Test positivity varied across age (0-4: 19.8%, 5-17: 1.8%, adults: 0.7%), regions (7.6-16.1%), settings (inpatient 4.7%, outpatient 14.2%), and test indication (5.0-35.9%). When compared to age, setting or indication-specific positivity, bias due to using NREVSS positivity to correct for untested ARIs ranged from - 76% to 3556%. CONCLUSIONS: RSV-test positivity depends on the characteristics of patients for whom those tests were ordered. NREVSS-based correction for RSV-under-ascertainment underestimates the true incidence among children and overestimate rates among adults. Demographic-specific detail on testing practice and positivity can improve the accuracy of RSV-incidence estimates.

Respiratory syncytial virus testing capabilities and practices among National Respiratory and Enteric Virus Surveillance System laboratories, United States, 2016.

BACKGROUND: Laboratory tests to detect respiratory syncytial virus (RSV) vary in sensitivity and specificity. Diagnostic testing practices can impact RSV disease diagnosis and burden estimates. OBJECTIVES: We surveyed a sample of laboratories that participated in the National Respiratory and Enteric Virus Surveillance System (NREVSS) in 2015-2016 to understand RSV testing, diagnostic capabilities, and practices. STUDY DESIGN: We distributed surveys in fall 2016 to NREVSS laboratories using an internet survey platform. We conducted a descriptive analysis of survey responses and stratified results by self-identified children's hospital laboratories (CHL, i.e. laboratories affiliated with or in a children's hospital) or general hospital laboratories (GHL, i.e. laboratories that performed analysis on specimens from only adults or adults and children). RESULTS: We sampled 367 (82.5%) of 445 eligible NREVSS laboratories with a 35.7% response rate; 11.5% (n = 15) were CHLs. All CHLs had PCR-based assay capability to test for RSV compared to 48.7% of GHLs (p < 0.001), and it was the most frequent method used by CHLs (n = 9, 75.0%). GHLs used rapid antigen detection tests most frequently (n = 65, 60.2%) to detect RSV compared to CHLs (p = 0.02, n = 3, 25.0%). Almost half (n = 41, 48.2%) of GHLs reported specimen submission from adults ≥50 years for RADTs. CONCLUSIONS: Laboratory testing and diagnostic capabilities differed by whether laboratories self-identified as a CHL or GHL. Many GHLs reported use of RADTs in adults ≥50 years, a less sensitive diagnostic method for this population compared to PCR-based assays. RADT use in adults might miss RSV cases and affect diagnoses and disease burden estimates.

Laboratory testing trends for respiratory syncytial virus, 2007-2011.

BACKGROUND: Antigen detection tests have been the most common diagnostic assay used to detect and diagnose respiratory syncytial virus (RSV). The utility and increased sensitivity of polymerase chain reaction (PCR) tests have been reported; however, their use in US hospital laboratories is not well characterized. OBJECTIVE: To describe changes in RSV test types used by US hospital-affiliated laboratories, focusing on PCR testing prevalence. STUDY DESIGN: Data were collected from 480 to 666 laboratories each RSV season (2007-2008 through 2010-2011) across 50 states, the District of Columbia, and Puerto Rico. A descriptive analysis was conducted using this convenience sample of RSV tests conducted from November to April each season. Total numbers and types of RSV tests performed were reported weekly and weekly proportions by test type were calculated. Kendall τ rank correlation was used to quantify associations between time and proportions of each test type. RESULTS: PCR tests accounted for 2%, 3%, 16%, and 21% of weekly tests (total range, 381,068-481,654 over 4 seasons) conducted each season from 2007 to 2011, respectively. The proportion of laboratories reporting ≥1 PCR tests was 4%, 5%, 10%, and 16%, respectively. Decreases in antigen testing and viral culture were similarly observed. CONCLUSIONS: Although antigen detection was the predominant test type reported in the sample of US hospital laboratories for RSV testing, PCR use increased to >20% of tests reported. These results demonstrate the increasing contribution of PCR to RSV surveillance. RSV surveillance systems relying solely on antigen detection results will not capture an increasing proportion of RSV test results.

Influenza-related health care utilization and productivity losses during seasons with and without a match between the seasonal and vaccine virus B lineage.

OBJECTIVE: To assess and compare direct medical costs (incurred by payers) and indirect productivity losses (incurred by employers) associated with influenza seasons with matched or mismatched circulating and vaccine containing influenza B lineages. METHODS: A retrospective analysis, using two MarketScan databases, for the years 2000-2009. Each influenza season was categorized as matched or mismatched after comparing that season's circulating influenza B lineage and the vaccine influenza B lineage. Patients selected had at least one diagnosis claim for influenza (ICD-9-CM code 487.xx [influenza] or 488.1 [H1N1]) during an influenza season. We assessed the incidence of influenza (overall and influenza B), influenza-related medical utilization and associated costs, and productivity losses for each season. RESULTS: The four matched seasons had lower average influenza incidence (overall incidence per 100,000 plan members: 509; 95% confidence interval [CI]: 505-512) than the five mismatched seasons (748; 95% CI: 745-751). The mismatched seasons had lower influenza B incidence (average incidence per 100,000 plan members: 126; 95% CI: 125-128) than the matched seasons (165; 95% CI: 163-167). The average, per-patient, total influenza-related medical costs in the mismatched seasons ($300.83; range: $245.38-$371.58) were approximately $61.00 higher than in the matched seasons ($239.43; range: $201.49-$264.01). The mismatched seasons had greater average per-patient, influenza-related productivity-loss costs than the matched seasons (mean: $237.31 vs. $175.10). CONCLUSION: CDC data showed that influenza A was the predominant circulating strain during seasons in which the circulating influenza B lineage did not match the vaccine influenza B lineage. This resulted in lower influenza B incidence during the mismatched seasons. However, the average, per-patient, influenza-related direct medical costs and indirect productivity losses were higher during the mismatched seasons. Additional research is required to determine if these higher costs can be attributed to influenza B infections and if the influenza severity varies during mismatched seasons.