Risk Factors for Acute Rheumatic Fever: Literature Review and Protocol for a Case-Control Study in New Zealand

Abstract

Acute rheumatic fever (ARF) and its sequela, rheumatic heart disease (RHD), have largely disappeared from high-income countries. However, in New Zealand (NZ), rates remain unacceptably high in indigenous Māori and Pacific populations. The goal of this study is to identify potentially modifiable risk factors for ARF to support effective disease prevention policies and programmes. A case-control design is used. Cases are those meeting the standard NZ case-definition for ARF, recruited within four weeks of hospitalisation for a first episode of ARF, aged less than 20 years, and residing in the North Island of NZ. This study aims to recruit at least 120 cases and 360 controls matched by age, ethnicity, gender, deprivation, district, and time period. For data collection, a comprehensive pre-tested questionnaire focussed on exposures during the four weeks prior to illness or interview will be used. Linked data include previous hospitalisations, dental records, and school characteristics. Specimen collection includes a throat swab (Group A Streptococcus), a nasal swab (Staphylococcus aureus), blood (vitamin D, ferritin, DNA for genetic testing, immune-profiling), and head hair (nicotine). A major strength of this study is its comprehensive focus covering organism, host and environmental factors. Having closely matched controls enables the examination of a wide range of specific environmental risk factors.

Keywords: acute rheumatic fever; case-control; crowding; environmental tobacco smoke; group A streptococcus; health care access; housing; rheumatic heart disease; risk factors; skin infection; sore throat.

Figure 1

Acute rheumatic fever (ARF) incidence by year, initial hospitalisation rate per 100,000 with 95% CIs, 1995 to 2014.

Figure 2

ARF incidence by month, initial hospitalisation numbers, average for 2010 to 2014.

Figure 3

ARF incidence by District Health Board (DHB) for children aged <20 years, average annual initial hospitalisation rate per 100,000, 2010–2014.

Figure 4

ARF incidence by single year of age, average annual initial hospitalisation number, 2010–2014.

Figure 5

ARF incidence by prioritised ethnicity and year, initial hospitalisation rate per 100,000, 5–14 year olds, 1995 to 2014.

Figure 6

ARF incidence by prioritised ethnicity and deprivation level, initial hospitalisation rate per 100,000, 5–14 year olds, average for 2010–2014.

Figure 7

Coded RHD initial hospitalisations and deaths by year, 1995 to 2014.

Figure 8

Causal pathway from GAS exposure to ARF and RHD showing major hypothesised groups of risk and protective factors.