Table S1.

Sub-analysis of letter recipients with medication filled after letter was sent (n=284)

Linear regression analysis of change in PDC – change in 6-month PDC from before the mailed letter to after the mailed letter
	Beta (standard error)	P-value
Language of letter	−0.009 (0.044)	0.834
Age	−0.001 (0.002)	0.478
Gender	−0.001 (0.033)	0.980
Ethnicity	−0.030 (0.021)	0.153
Region: Texas vs out of state	0.045 (0.022)	0.045
Low income subsidy eligibility	0.043 (0.037)	0.251
Medication category	−0.007 (0.022)	0.755
Generic vs brand	−0.060 (0.077)	0.436
Day supply	0.144 (0.034)	<0.001
Copay	−0.001 (0.003)	0.802
Pharmacy type	0.032 (0.104)	0.762

Abbreviation: PDC, proportion of days covered.