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

Table 3 Estimated effects of rare disease legislation on SSc scientific output

	M1	M2	M3
All countries (167 countries, 7649 observations)	0.937*** (0.707, 1.168)	0.933*** (0.701, 1.165)	0.628*** (0.390, 0.867)
HICs (52 countries, 2451 observations)	0.807*** (0.552, 1.062)	0.813*** (0.553, 1.073)	0.443* (0.076, 0.811)
MICs (89 countries, 4026 observations)	0.652*** (0.277, 1.026)	0.640** (0.264, 1.017)	0.447* (0.051, 0.842)
Country fixed effects	Uncontrolled	Controlled	Controlled
Year fixed effects	Uncontrolled	Uncontrolled	Controlled

Panel regression assessed effects of rare disease legislation on SSc scientific output measured by ln of SSc publications. With the legislation dummy variable, value one was assigned to countries from the year after rare disease legislation adoption, and zero to other conditions. Effect heterogeneity among countries of different income levels was evaluated using group analysis. Coefficients of legislation in LICs were not reported, for none of the 26 countries had rare disease legislation. Country covariates available were controlled in all three models (M1–M3). Country fixed effects and year fixed effects were included sequentially in M2 and M3
HICs high-income countries, MICs middle-income countries, SSc systemic sclerosis
***p < 0.001; **p < 0.01; *p < 0.05

ISSN: 1750-1172