Effects of socio-economic factors on research over systemic sclerosis: an analysis based on long time series of bibliometric data

BACKGROUND: Systemic sclerosis (SSc) is a rare detrimental disease warranting global research efforts. Evaluating how socio-economic factors impact country research output on SSc could help to identify solutions advancing research. METHODS: Publication production on SSc during 1969–2018 and data for structural and policy factors for WHO member countries were collected from public sources. Associations between SSc research output and country-level factors were investigated through panel regression. Difference-in-differences analysis further assessed the causal effects of rare disease legislation. RESULTS: SSc publications demonstrated exponential growth (r = 0.9410, as against an r = 0.8845 after linear adjustment), but were concentrated in high-income countries (HICs). Ten countries, nine of which were HICs, published 12,261 (77.5%) SSc publications but another 87 countries produced none. Gross domestic products (GDP), population and expenditure on research and development were positively associated with SSc publications (p < 0.001). Higher health expenditure was only found to be associated with increased SSc publications in HICs (p < 0.001). Rare disease legislation increased annual publication production by 62.8% (95% CI 0.390–0.867; p < 0.001) averagely. In middle-income countries (MICs), the effect was especially swift and lasting. No significant impact was found with GDP per capita, female percentage, and political indicators. CONCLUSIONS: SSc research output increased over time with substantial country disparities. Effective health policies facilitating research should be expanded especially among MICs to accelerate research advancement. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13023-021-02149-w.