Table 6.

Adjusted Associations Between Personal Continuity Measures and Incident PIM

Continuity Measure	0-2 Chronic Conditions		3-4 Chronic Conditions		5-18 Chronic Conditions		Total Population
Continuity Measure	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value
Usual provider of care		.002		.44		<.001		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.12 (1.05-1.18)		0.97 (0.92-1.03)		0.94 (0.91-0.98)		0.97 (0.94-1.00)
High tertile	1.04 (0.98-1.12)		0.96 (0.92-1.02)		0.90 (0.87-0.94)		0.92 (0.89-0.95)
Bice-Boxerman Index		<.001		.21		.002		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.23 (1.16-1.31)		1.05 (0.99-1.10)		0.99 (0.95-1.03)		1.07 (1.04-1.10)
High tertile	1.13 (1.06-1.20)		1.01 (0.96-1.07)		0.93 (0.90-0.97)		0.99 (0.95-1.02)
Herfindahl Index		.04		.01		<.001		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.01 (0.95-1.08)		0.96 (0.91-1.01)		0.92 (0.89-0.96)		0.92 (0.89-0.94)
High tertile	0.94 (0.88-1.00)		0.92 (0.87-0.97)		0.87 (0.83-0.90)		0.85 (0.82-0.88)

PIM = potentially inappropriate medication; ref = reference category; RR = rate ratio.
Notes: Results of multilevel negative binomial regression analysis adjusted for sex and age, and stratified by number of chronic conditions. The RRs are exponential regression coefficients. Total population was 25,854; there were 7,992 patients with 0-2 chronic conditions, 8,349 patients with 3-4 chronic conditions, and 9,513 patients with 5-18 chronic conditions.