Risk factors for acute rheumatic fever: A case-control study

BACKGROUND

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) remain an inequitable cause of avoidable suffering and early death in many countries, including among Indigenous Māori and Pacific populations in New Zealand. There is a lack of robust evidence on interventions to prevent ARF. This study aimed to identify modifiable risk factors, with the goal of producing evidence to support policies and programs to decrease rates of ARF.

METHODS

A case-control study was undertaken in New Zealand using hospitalised, first episode ARF cases meeting a standard case-definition. Population controls (ratio of 3:1) were matched by age, ethnicity, socioeconomic deprivation, location, sex, and recruitment month. A comprehensive, pre-tested questionnaire was administered face-to-face by trained interviewers.

FINDINGS

The study included 124 cases and 372 controls. Multivariable analysis identified strong associations between ARF and household crowding (OR 3·88; 95%CI 1·68-8·98) and barriers to accessing primary health care (OR 2·07; 95% CI 1·08-4·00), as well as a high intake of sugar-sweetened beverages (OR 2·00; 1·13-3·54). There was a marked five-fold higher ARF risk for those with a family history of ARF (OR 4·97; 95% CI 2·53-9·77). ARF risk was elevated following self-reported skin infection (aOR 2·53; 1·44-4·42) and sore throat (aOR 2·33; 1·49-3·62).

INTERPRETATION

These globally relevant findings direct attention to the critical importance of household crowding and access to primary health care as strong modifiable causal factors in the development of ARF. They also support a greater focus on the role of managing skin infections in ARF prevention.

FUNDING

This research was funded by the Health Research Council of New Zealand (HRC) Rheumatic Fever Research Partnership (supported by the New Zealand Ministry of Health, Te Puni Kōkiri, Cure Kids, Heart Foundation, and HRC) award number 13/959.

Impact of viral symptoms on the performance of the modified centor score to predict pediatric group A streptococcal pharyngitis

BACKGROUND

Clinicians use the Modified Centor Score (MCS) to estimate the risk of group A streptococcal (GAS) pharyngitis in children with sore throat. The Infectious Diseases Society of America (IDSA) recommends neither testing nor treating patients with specific viral symptoms. The goal of this study is to measure the impact of those symptoms on the yield of GAS testing predicted by the MCS.

METHODS

Retrospective cohort study of all patients aged 3-21 years presenting with sore throat and tested for GAS in a pediatric emergency department (ED) in 2016. After identifying all patients tested for GAS, we used natural language processing (NLP) to identify the subgroup complaining of sore throat. We abstracted all MCS variables as well as symptoms suggestive of a viral etiology per the IDSA guideline (conjunctivitis, coryza, cough, diarrhea, hoarseness, ulcerative oral lesions, viral exanthema). We calculated the proportion of patients who tested positive for GAS by MCS with and without viral symptoms.

RESULTS

Of the 1574 patients included, 372 patients (24%) tested GAS positive. Patients with at least one viral symptom had a reduced GAS risk compared to those without any of the viral symptoms 91/547 (17% GAS positive) vs. 281/1027 (27%), odds ratio 0.53 (95% CI 0.41-0.69).

CONCLUSIONS

The presence of viral symptoms specified by the IDSA alters the predicted yield of testing by traditional MCS. Clinicians may consider adjusting interpretation of a patient's MCS based on the presence of viral symptoms, but viral symptoms may not always fully obviate the need for GAS testing.