Addressing patient’s unmet social needs: disparities in access to social services in the United States from 1990 to 2014, a national times series study

Table 1 Differences in the tract level density of social service providers by quartiles of 1990 poverty rate and 1990 poverty rate by year interactions

Predictor Variables	Difference in provider counts/Km² (95% CI) P-value For tracts in the second tertile of population density (248—1,479 people/Km²)	Difference in provider counts/Km² (95% CI) P-value For tracts in the third tertile of population density (> 1,479 people/Km²)
Quartile of 1990 poverty rate
1^st Quartile (low poverty)	Ref	Ref
2^st Quartile	0.04 (0.02, 0.05) p < 0.001	0.30 (0.20, 0.41) p < 0.001
3^st Quartile	0.14 (0.10, 0.17) p < 0.001	0.79 (0.66, 0.93) p < 0.001
4^st Quartile (high poverty)	0.48 (0.43, 0.54) p < 0.001	1.45 (1.33, 1.57) p < 0.001
Quartile of 1990 poverty rate * Year
1^st Quartile * Year	Ref	Ref
2^st Quartile * Year	0.003 (0.002, 0.005) p < 0.001	0.04 (0.02, 0.05) p < 0.001
3^st Quartile * Year	0.009 (0.005, 0.013) p < 0.001	0.06 (0.05, 0.07) p < 0.001
4^st Quartile* Year	0.03 (0.025, 0.033) p < 0.001	0.09 (0.08, 0.1) p < 0.001

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