Evaluation of two rapid detection assays for identification of respiratory syncytial virus in nasopharyngeal secretions of young children

Diagnostic Accuracy of Rapid Antigen Detection Tests for Respiratory Syncytial Virus Infection: Systematic Review and Meta-analysis

Respiratory syncytial virus (RSV) rapid antigen detection tests (RADT) are extensively used in clinical laboratories. We performed a systematic review and meta-analysis to evaluate the accuracy of RADTs for diagnosis of RSV infection and to determine factors associated with accuracy estimates. We searched EMBASE and PubMed for diagnostic-accuracy studies of commercialized RSV RADTs. Studies reporting sensitivity and specificity data compared to a reference standard (reverse transcriptase PCR [RT-PCR], immunofluorescence, or viral culture) were considered. Two reviewers independently extracted data on study characteristics, diagnostic-accuracy estimates, and study quality. Accuracy estimates were pooled using bivariate random-effects regression models. Heterogeneity was investigated with prespecified subgroup analyses. Seventy-one articles met inclusion criteria. Overall, RSV RADT pooled sensitivity and specificity were 80% (95% confidence interval [CI], 76% to 83%) and 97% (95% CI, 96% to 98%), respectively. Positive- and negative-likelihood ratios were 25.5 (95% CI, 18.3 to 35.5) and 0.21 (95% CI, 0.18 to 0.24), respectively. Sensitivity was higher in children (81% [95% CI, 78%, 84%]) than in adults (29% [95% CI, 11% to 48%]). Because of this disparity, further subgroup analyses were restricted to pediatric data (63 studies). Test sensitivity was poorest using RT-PCR as a reference standard and highest using immunofluorescence (74% versus 88%; P < 0.001). Industry-sponsored studies reported significantly higher sensitivity (87% versus 78%; P = 0.01). Our results suggest that the poor sensitivity of RSV RADTs in adults may preclude their use in this population. Furthermore, industry-sponsored studies and those that did not use RT-PCR as a reference standard likely overestimated test sensitivity.

Prevalence of respiratory syncytial virus infection among hospitalized children presenting with acute lower respiratory tract infections

OBJECTIVE

To evaluate the prevalence of RSV among hospitalized young children presenting with ALRI in Bangalore, India.

METHODS

Respiratory syncytial virus (RSV) antigen detection was performed by direct fluorescent antibody (DFA) staining on 77 nasopharyngeal wash samples collected from hospitalized children below 2 years of age with a diagnosis of acute lower respiratory tract infection (ALRI).

RESULTS

Out of 77 samples tested for RSV with DFA, 17 (22.1%) were found RSV-positive with a mean age of 8.24 ± 7.21 months (M:F = 1.8:1). Three children had congenital cardiac disease and one child had a history of prematurity. One child had re-infection within one month of primary infection. RSV-infected children were more likely to have a diagnosis of bronchiolitis than RSV-negative children (p < 0.001).

CONCLUSIONS

RSV infection is a significant cause of morbidity among children presenting with ALRI in southern India. In resource-limited settings, DFA can be used as an important tool for rapid detection of RSV and can potentially eliminate prolonged hospitalization and unnecessary use of antibiotics.

Diagnostic assays for respiratory syncytial virus disease

Respiratory syncytial virus (RSV) infection in the United States and worldwide is a major cause of morbidity and mortality and of outpatient visits, hospitalizations, and increased healthcare costs. Effective diagnosis of viral respiratory infections, as well as recognition and understanding of the benefits and limitations of diagnostic laboratory testing, is essential. Serology is not useful for diagnosing acute respiratory illness. Antigen-based assays are widely available, easy to use, provide rapid results, and are inexpensive; however, they are less sensitive than cell culture utilizing good specimen collection and processing techniques. Cell culture, which was previously considered the gold standard for identification of respiratory viruses, in many settings is being replaced by nucleic acid amplification assays that have even greater sensitivity and provide more rapid results. Although available chiefly at large hospitals and reference laboratories, molecular assays may fulfill the need for more sensitive and rapid diagnosis of illnesses caused by respiratory viruses. The seasonality of RSV as measured by nucleic acid amplification-based assays appears to be broader with better identification of patient populations that harbor RSV between yearly epidemic peaks compared with the seasonality of RSV as measured by the older techniques. As these new diagnostic methodologies emerge, guidelines will be needed to direct their appropriate use in the diagnostic laboratory.