Although laboratory diagnosis of respiratory viruses has been widely studied, there is a relative insufficiency of literature examining the impact of specimen type on the laboratory diagnosis of influenza A and B. In a clinical study comparing the FLU OIA test with 14-day cell culture, clinical specimens from nasopharyngeal swabs, throat swabs, nasal aspirates, and sputum were obtained from patients experiencing influenza-like symptoms. A total of 404 clinical specimens were collected from 184 patients. Patients were defined as influenza positive if the viral culture of a specimen from any sample site was positive. Patients were defined as influenza negative if the viral cultures of specimens from all sample sites were negative. By this gold standard, culture and FLU OIA test results for each sample type were compared. For each of the four specimen types, the viral culture and FLU OIA test demonstrated equal abilities to detect the presence of influenza A or B virus or viral antigen. Sputum and nasal aspirate samples were the most predictive of influenza virus infection. Throat swabs were the least predictive of influenza virus infection, with both tests failing to detect influenza virus in nearly 50% of the throat samples studied.

ABSTRACT. Objective. Since the 1990 publication of a decision analysis, in which the treatment of pharyngitis in children was evaluated, a number of assumptions important in that analysis have changed. Updating many of the assumptions and costs used in that analysis to reflect the conditions currently found in a large, suburban pediatric practice, a cost-effectiveness analysis was performed in which four strategies for the treatment of pharyngitis were considered: treat all, high-sensitivity antigen test, culture, and high-sensitivity antigen test with culture confirmation.Design. Decision analysis.Results. Using microbiology data from the 13 published studies in which a high-sensitivity antigen test (Strep A OIA; BioStar Inc., Boulder, CO) and blood agar plate culture were evaluated against a variety of gold standards, the sensitivity and specificity of the highsensitivity antigen test were 89.1% and 95%, respectively. The sensitivity and specificity of blood agar plate throat culture were 83.4% and 99%, respectively. Penicillin V was used as the treatment of choice for uncomplicated pharyngitis; erythromycin was used in cases of penicillin allergy. Rates of suppurative and nonsuppurative complications reflect those currently seen in the United States. Other assumptions and cost data were taken from a large, suburban pediatric practice and its affiliated tertiary care medical center, except where noted.Despite the potential induction of resistance and the high number of allergic reactions associated with the treat-all strategy, this strategy had the lowest average cost per patient encounter and was the most cost-effective in terms of dollars per suppurative and nonsuppurative complication prevented. Of the strategies in which a diagnostic test was used, the high-sensitivity antigen test strategy had the lowest average cost and was the most cost-effective. The high-sensitivity antigen test with culture confirmation strategy had the highest average cost and was the least cost-effective.In the sensitivity analyses, a number of assumptions used in the original model were varied within a reasonable range. Under most conditions, the treat-all strategy remained the most cost-effective strategy used. One notable exception: when the wholesale cost of the antibiotic exceeded $10.76, as would be seen if any cephalosporin were used as the primary therapy of uncomplicated pharyngitis, the high-sensitivity antigen test strategy became the most cost-effective strategy.Under most conditions, the high-sensitivity antigen test strategy was the most cost-effective of the strategies in which a diagnostic test was used. Notable exceptions included: 1) conditions in which there was a low probability of streptoccal infection, 2) the use of an antigen test whose sensitivity is inferior to that of culture, and 3) during an epidemic of acute rheumatic fever.Culture confirmation of a negative high-sensitivity antigen test is the most cost-effective testing strategy only under conditions in which the probability of acute rheumatic fever a...

The purpose of the present study was to determine whether the availability of results from a high-sensitivity, rapid test for group A streptococci (Strep A OIA; BioStar, Inc., Boulder, Colo.) improves physician outcome. The study population included 465 consecutive patients with symptoms of acute pharyngitis seen in two outpatient clinics in a large suburban medical center; one clinic, a walk-in clinic (WIC), primarily saw adult patients, and one clinic, a pediatric and adolescent medicine clinic (PED), primarily saw pediatric patients. We measured improvement in physician outcome by comparing physician intent for prescribing an antibiotic based on clinical impression with physician practice once the results of the Strep A OIA were known. Based upon intent, the physicians seeing WIC patients (WIC physicians) would have prescribed an appropriate antibiotic course for 42% of patients with cultures positive for group A beta-hemolytic streptococci (GABHS) and 61% of patients with cultures negative for GABHS. After receiving the results of the Strep A OIA, WIC physicians prescribed an appropriate antibiotic course for 81% of patients with positive cultures and 72% of patients with negative cultures. Based upon intent, the physicians seeing PED patients (PED physicians) would have prescribed an appropriate antibiotic course for 35% of patients with positive cultures and 77% of patients with negative cultures. After receiving the results of the Strep A OIA, PED physicians prescribed an appropriate antibiotic course for 90% of patients with positive cultures and 81% of patients with negative cultures. Based on a 14.5% prevalence of GABHS among WIC patients, Strep A OIA improved the overall WIC physician outcome from 58 to 74%. Based on a 31.5% prevalence of GABHS among PED patients, Strep A OIA improved the PED physician outcome from 64 to 84%. Had Strep A OIA alone guided therapeutic choice, physicians would have prescribed an appropriate antibiotic course for 95% of the patients at the time of the initial encounter. We conclude that the use of Strep A OIA improves physician outcome.

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