Table 3.

Associations of commonly investigated factors with potentially inappropriate medication (PIM) use

	Patient factors													Clinician factors				System factors
	No. of medicationsa	Increasing ageb	Female sexc	Race and ethnicityd	Level of education	Marital status	No. outpatient/ED visits	No. of hospital admissions	No. of prescribers	More medical comorbidity	Presence of psychiatric comorbidity	Worse functional status	Cognitive impairment	Clinician age, sex, years of experience	Time spent	Proportion of patients >75 years	Specialtye	Geographic region (south)	Rural site of care	Insurance typef
Administrative data
Zhang (2010)[27]g
Woelfel (2011)[20]	+	0	0
Blackwell (2012)[29]	+	−	+	+						+								+		+
Holmes (2013)[31]	+	0	+	+				+	+	0
Lund (2013)[32]																		+	+
Jiron (2016)[35]	+	−	+	+			0	0	+				+				+	+
Kester, 2016)[36]		+	+							0	+							+		+
Chart review
Buck (2008)[25]	+	+	+	0			+
Hu (2012)[28]	+	−	0			0
Prithviraj (2012)[30]	+	0	0	0	0	0				0	0	0	0
Nightingale (2015)[39]	+	0	0	0						+		0
DiNapoli (2016)[34]		0		0						0	+
Ie (2017)[40]																+
Nationally representative survey
Zhang (2011)[21]	+	0	+	0	0													+	0	0
Kachru (2015)[22]		−	+	0	−	0					+	0						+	0
Extavour (2016)[24]	+		+	0							+				−		0		0	0
Miller (2016)[23]	+	−	0	0	0							0						0	0	0
Swanoski (2017)[37]		−	+	+			+											+
Other
Weston (2010)[26]	+	0	+		0						+	0	0
Koyama (2013)[33]													+
Mattos (2016)[38]	+	0	0	0	0	0					+								+
Shade (2017)[41]	+	0							0	0	0

No., number; +, positive association with risk of PIM use; −, negative association with risk of PIM use; 0, no statistically significant association with risk of PIM use.

^aNumber of medications examined as a continuous and categorical variable across studies.

^bAge was examined as a continuous and categorical variable with categories ranging from 5 to 20 years.

^cMale sex was examined in all 16 studies and was significant in 0 studies.

^dResults were conflicted with varying reference groups.

^eSpecialties examined varied.

^fResults were conflicting with studies comparing varying payer types. Two studies, which looked specifically at Medicare–Medicaid dual eligibility, found a significant positive association.

^gThis study did not examine any of the listed characteristics, it examined adjusted gross spending, see Table 1.