PEDIATRICS Vol. 121 No. 2 February 2008, pp. 229-234 (doi:10.1542/peds.2007-0484)
ARTICLE |
Burden and Economic Cost of Group A Streptococcal Pharyngitis
a Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, Massachusetts
b Division of Infectious Diseases, Children's Hospital, Boston, Massachusetts
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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OBJECTIVE. Our aim was to describe the morbidity, medical costs, and nonmedical costs associated with group A streptococcal pharyngitis in school-aged children.
METHODS. Our study population included parents of children diagnosed as having group A streptococcal pharyngitis at 2 pediatric practice sites in the Boston, Massachusetts, metropolitan area. Telephone interviews were conducted with parents of eligible children, who were asked questions about health care utilization, medications, and time missed from work or school, for calculation of medical and nonmedical costs associated with illness.
RESULTS. One hundred thirty-five parents completed interviews between October 2005 and January 2006. Older children were significantly more likely to present with headache, compared with those 
5 years of age. No significant differences between older and younger children were found for rates of sore throat, fever, abdominal pain/nausea/vomiting, or rash. Children missed a mean of 1.9 days (range: 0–7 days) of school/day care, and 42% of parents missed a mean of 1.8 days of work. A second parent or caregiver also missed a mean of 1.5 days in 14% of families. The total societal cost per case of group A streptococcal pharyngitis was $205 (medical: $118; nonmedical: $87).
CONCLUSIONS. The societal cost of group A streptococcal pharyngitis is substantial, with almost one half being attributable to nonmedical costs. Through extrapolation from this experience, the total cost of group A streptococcal pharyngitis among children in the United States ranges from $224 to $539 million per year.
Key Words: economic burden • pharyngitis • group A streptococcus • vaccine
Abbreviations: GAS—group A streptococcus
Approximately 7.3 million outpatient physician visits attributable to sore throat occur each year among children in the United States, and group A streptococcus (GAS) is responsible for 15% to 36% of cases.1 GAS, or Streptococcus pyogenes, is the most common bacterial cause of pharyngitis and can lead to acute rheumatic fever.2 GAS can also cause life-threatening illnesses such as streptococcal toxic shock syndrome and necrotizing fasciitis. Approximately 9700 cases of invasive disease and 1300 deaths are attributed to GAS each year.3,4
Considerable overlap has been noted between GAS strains that cause pharyngitis in school-aged children and isolates from cases associated with invasive disease in the community.5–7 This overlap suggests that school-aged children (the population in which pharyngitis occurs most frequently) serve as a reservoir of infection for the community. Therefore, a GAS vaccine not only may prevent pharyngitis and invasive disease in school-aged children but also may reduce the number of cases of invasive disease in the surrounding community, by reducing carriage and transmission of the organism.8,9
A multivalent vaccine targeting strains that cause pharyngitis, invasive disease, and rheumatic fever has already completed phase I trials in the United States and phase I/II trials in Canada.8,10 If the vaccine proves efficacious, then it not only will have the potential to prevent disease associated with GAS but also may reduce antibiotic prescribing and decrease the rate of antibiotic resistance in the community. Before vaccine implementation can be considered, the programmatic costs must be weighed against the burden of GAS morbidity on society. Our aim was to describe the morbidity, medical costs, and nonmedical costs associated with GAS pharyngitis in school-aged children.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Study Population
The study population included parents of children diagnosed as having GAS pharyngitis at 2 pediatric practice sites in the Boston, Massachusetts, metropolitan area. We identified 288 episodes of GAS pharyngitis among children who were seen at 1 urban practice or 1 suburban practice, in urgent care visits, between October 1, 2005, and January 25, 2006. Families were considered eligible for the study if the child or adolescent was <18 years of age, had an initial presenting complaint of fever, sore throat, rash, or nausea/vomiting/abdominal pain, had a confirmed diagnosis of GAS pharyngitis with positive rapid streptococcus test or throat culture results, and was not considered a GAS carrier. Children who are considered GAS carriers may harbor GAS in their throats regardless of whether they are symptomatic. The cost of carriers was not included in our analysis, because such children do not necessarily have disease attributable to GAS. Fifty-two cases were excluded from the study for the following reasons: incorrect address or telephone number (21 cases), child had a sibling already enrolled in the study (12 cases), child was previously enrolled in the study (7 cases), child was taken to the doctor by someone other than a parent or guardian (7 cases), parent or guardian did not understand that the child had GAS pharyngitis (3 cases), or parent or guardian was non–English-speaking (2 cases).
Survey
Families of children who were eligible for the study were mailed a letter inviting them to participate in a one-time structured telephone survey. Among those who agreed to participate in the study, telephone surveys were completed with parents or guardians 2 to 6 weeks after the initial clinic visit. The telephone survey was designed to include questions about morbidity, medical costs, and nonmedical costs, similar to a previously published survey.11 Survey questions included questions about duration of symptoms, outpatient visits, emergency department visits, hospitalizations, antibiotics, other prescription medications for streptococcal sore throat, drug allergies, time missed from work or school, personal time missed, and out-of-pocket expenses, such as those for transportation, babysitting, and over-the-counter medications. We also asked families whether and how many other household members subsequently developed streptococcal infection.
Medical Costs
Estimates of medical costs were calculated by linking health service utilization data with national estimates of the costs of services. National cost estimates, rather than local costs, were used to improve the generalizability of our findings. The cost of services such as visits to the doctor's office or an emergency department were found in the Medicare Annual Physician Fee Schedule.12 The cost of performing a rapid streptococcus test or culture was estimated by using the American Academy of Pediatrics Medicaid reimbursement survey,13 whereas the costs of prescription medications were calculated by using average wholesale prices from the 2005 Drug Topics Red Book.14
Nonmedical Costs
Nonmedical costs were estimated in accordance with the guidelines of the National Panel on Cost-Effectiveness in Health and Medicine.15 Work-loss costs for adults were based on the time missed from work multiplied by the national median wage rate for the age and gender of the individual affected.16,17 Personal time costs, defined as time spent away from work or household duties, were calculated on the basis of personal time missed multiplied by the national median wage rate, assuming that personal time was valued similarly to work time.15 Information on deductibles and copayments made at the visit was gathered in the study. Child care costs were estimated to be $10 per hour.18 The cost of transportation to the doctor's office was calculated by using the average price of 1 gallon of gasoline19 divided by the expected miles per gallon of all light-duty vehicles20; added to this was the mean of the standard mileage rates set by the Internal Revenue Service.21 Some participants took public transportation, and those costs were added to the cost of driving for an overall transportation cost. The costs of nonprescription medications were calculated by using average wholesale prices from the 2005 Drug Topics Red Book.14
Data Analyses
All costs were adjusted to 2006 US dollars.22 Descriptive analyses, including means, medians, ranges, and percentages, were performed. Survey responses were extrapolated to the US population by assuming that 7.3 million visits attributable to pharyngitis occur annually among children and 15% to 36% of cases are attributable to GAS infection.1 The secondary attack rate was calculated as the number of secondary cases of GAS infection divided by the number of susceptible household members (excluding the index case). For comparison of demographic and clinical characteristics between participants and nonparticipants, 
2 tests were used. P values of <.05 were considered statistically significant. All analyses were performed by using Stata 9.0 software (Stata Corp, College Station, TX).
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Study Population
Of 236 potentially eligible cases, 1 parent from each of 135 families (57%) completed a telephone interview. There were no significant differences between participants who completed the interview and those who did not, with respect to site or age or gender of the child. The mean age of the children enrolled in the study was 8.8 years, and 52% of the children were female (Table 1).
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Morbidity
Children diagnosed as having GAS pharyngitis had initial presenting complaints of sore throat (92%), fever (50%), headache (21%), abdominal pain/nausea/vomiting (13%), and rash (5%) (Table 2). Older children (
6 years of age) were significantly more likely to present with a headache, compared with younger children (P = .01). The mean and median times from the initial visit to resolution of symptoms associated with GAS pharyngitis were 4.5 days and 4 days (range: 0–24 days), respectively. At least 1 other family member developed GAS pharyngitis after the index case in 29% of families. Among the households where transmission occurred, a mean of 2.6 other family members (range: 1–6 family members) became sick. The mean secondary attack rate for GAS pharyngitis within families was 20% overall.
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Children missed a mean of 1.9 days (range: 0–7 days) of school or day care because of GAS pharyngitis. Fifty-seven (42%) of 135 parents missed a mean of 1.8 days of work (range: 0.5–12.0 days) to care for their child. In 14% of families, a second parent or caregiver missed a mean of 1.5 days (range: 1–3 days). In 2 families, a third caregiver missed a mean of 0.8 days (range: 0.5–1.0 days). Among caregivers who missed work, 80% were female. Respondents were also asked about any personal time missed during their child's illness. More than one half (54%) of the respondents reported missing a mean of 0.3 days of personal time (range: 0–4 days).
Health Services Utilization, Diagnostic Testing, and Treatment
Eighty-seven percent of children with GAS pharyngitis had 1 outpatient visit, whereas 13% had 2 outpatient visits (Table 3). Although 4% of children diagnosed as having GAS pharyngitis were seen in the emergency department, no child required hospitalization for complications attributable to pharyngitis. Most cases were diagnosed through rapid streptococcus testing alone, although 16% were diagnosed on the basis of throat cultures after negative rapid streptococcus test results were obtained.
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Seventy-nine percent of children received penicillin or amoxicillin for treatment of GAS pharyngitis (Table 3). Among the children given cephalexin or azithromycin, 100% and 73%, respectively, had a documented penicillin/amoxicillin allergy. Seven children (5%) were given a second antibiotic, either because of an allergic reaction to the first antibiotic or because symptoms recurred soon after treatment. Children
5 years of age were more likely to be given amoxicillin, compared with older children (52% vs 42%), although this was not a statistically significant difference. Caregivers also described giving over-the-counter medications for symptomatic treatment of GAS pharyngitis. Fifty-seven percent of children received ibuprofen alone, 21% received acetaminophen alone, and 15% received both ibuprofen and acetaminophen. Thirty-three percent reported using throat lozenges, throat sprays, or vapor rubs, and 20% reported using herbal supplements, teas, vitamins, or minerals.
Costs of GAS Pharyngitis
The mean medical and nonmedical costs per case were $118 and $87, respectively (Table 3). Medical costs were mostly attributable to outpatient visits (52%), followed by antibiotic treatment (24%) and diagnostic testing (17%) (Fig 1). Time costs (work missed and personal time) were responsible for 46% of nonmedical costs. The remainder was attributable to child care expenses (16%), transportation (15%), deductibles or copayments (15%), and over-the-counter medications (8%).
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When medical and nonmedical costs were added together, the total societal cost per case of GAS pharyngitis was $205. Nonmedical costs accounted for 42% of the total societal cost. Extrapolation of our results to the US population yielded estimated total costs attributable to GAS pharyngitis in children and adolescents of $224 million to $539 million annually.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Our study is the first to collect empiric data on the societal costs of GAS pharyngitis in children and adolescents. The societal cost per case was just over $200, with almost one half being attributable to nonmedical costs. The inclusion of nonmedical costs is important in considerations of the economic burden of illnesses. Other studies of vaccine-preventable diseases estimated that nonmedical costs accounted for 39% to 83% of the total cost.11,23–26 The societal cost per case of GAS pharyngitis exceeded that of viral respiratory tract infections ($80); however, it was estimated to be less than the cost per case of otitis media ($262) in children or pertussis ($397) in adolescents.11,25,26 Although the cost per case may be lower than that for other infections, GAS pharyngitis occurs frequently, resulting in an estimated national economic burden of $224 million to $539 annually. Furthermore, this estimate may be at the lower end of the range, because we did not include costs incurred by individuals who did not seek medical care or costs attributable to secondary cases. Given these findings and the recent development of new GAS vaccine candidates, the potential economic benefits of preventing GAS pharyngitis would be significant.
The morbidity of GAS pharyngitis in families was considerable. Children experienced symptoms for 4.5 days, on average, and missed a mean of 1.9 days of school; this would result in a substantial societal burden given the frequency of GAS pharyngitis among schoolchildren and the large number of school days missed because of illness in the United States.27 Parents also needed to miss a mean of 1.8 days of work to care at home for children with GAS pharyngitis. The secondary attack rate in families was relatively high at 20%, similar to findings in other studies that found attack rates of 23% among children and 9% among adults, and the impact of these secondary cases was not included in our analysis.28
The current 26-valent GAS vaccine candidate includes M-types known to cause pharyngitis, invasive disease, and acute rheumatic fever.8,10 Such a vaccine would be helpful in reducing the reservoir of GAS infection in the population, particularly if it were targeted at school-aged children.29 In addition to preventing pharyngitis, potential benefits of a routine vaccination program for school-aged children might include reductions in the transmission of GAS infection within the community. Rates of invasive disease and pharyngitis attributable to GAS infection in unvaccinated adults may decrease if transmission is interrupted, similar to results observed with the 7-valent pneumococcal conjugate vaccine.30–32 A reduction in the proportion of pharyngitis cases caused by GAS infection also may result in other unintended benefits for the United States, including decreases in unnecessary antibiotic use for pharyngitis in both children and adults, which in turn might decrease the level of antibiotic resistance seen in communities.30,33–35
Potential study limitations include the lack of generalizability because our sample size was limited, subjects lived in the Boston metropolitan area, subjects were English-speaking, and the majority of subjects had annual household incomes of more than $50000. In addition, our response rate was 57%, although we did not identify significant demographic differences between participants and nonparticipants. We might have unknowingly included GAS carriers who did not have true acute infections, which might have affected the overall cost of illness. Recall bias might have resulted in a less-accurate estimation of costs. We delayed interviews until 2 weeks had passed to include all downstream costs associated with a pharyngitis episode, such as time missed from work. To try to limit recall bias, however, we did complete the interviews within 6 weeks after the GAS pharyngitis episode. Finally, we did not include all possible economic costs in our estimate, such as costs incurred by sick family members, costs of missed days of school, and costs of complications associated with GAS pharyngitis, all of which may have increased the total societal burden significantly.
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CONCLUSIONS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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The burden and societal costs of GAS pharyngitis among children are substantial, with almost one half being attributable to nonmedical costs. The availability of a GAS vaccine not only would reduce the burden of GAS pharyngitis in the United States but also could have significant effects in reducing the worldwide incidence rates of pharyngitis, invasive disease, and acute rheumatic fever.
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ACKNOWLEDGMENTS |
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This study was supported by Agency for Healthcare Research and Quality grant 5 K08 HS013808-04 (to Dr Lee).
We thank the physicians at the Harvard Vanguard Medical Associates practice sites for their assistance with this study. We also acknowledge the contribution to this work by Charlene Gay and Dr Tracy Lieu in the Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care.
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FOOTNOTES |
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Accepted Jul 16, 2007.
Address correspondence to Grace M. Lee, MD, MPH, Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, 133 Brookline Ave, 6th Floor, Boston, MA 02215. E-mail: grace_lee{at}hphc.org
The authors have indicated they have no financial relationships relevant to this article to disclose.
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