. Author manuscript; available in PMC: 2013 Mar 20.

Published in final edited form as: JAMA. 2011 Oct 19;306(15):1688–1698. doi: 10.1001/jama.2011.1515

Table 2. Variables considered by studies in evaluating the risk of readmission.

Variable	Included in final model in (N) studies	Evaluated but not included in (N) studies	Not considered^* in (N) studies
Medical comorbidities
Specific diagnoses or comorbidity index	(24) ^{12-21, 23, 25-32, 53, 54, 57-59}	(0)	(3) ^{22, 24, 55}
Mental health comorbidities
Mental illness	(9) ^{13-15, 17, 18, 24, 25, 54, 59}	(4) ^{16, 20, 26, 58}	(11) ^{19, 22, 23, 28-32, 53, 55, 57}
EtOH/substance use	(11) ^{13-15, 17-19, 24-26, 53, 54}	(5) ^{16, 20, 28, 57, 59}	(8) ^{22, 23, 29-32, 55, 58}
Illness severity
Illness severity index	(1) ²⁴	(1) ⁵⁸	(19) ^{12, 13, 15-18, 20, 23, 26, 28-32, 53-55, 57, 59}
Lab findings	(4) ^{18, 30, 55, 57}	(1) ²⁸	(15) ^{12, 13, 15-17, 20, 23, 26, 29, 31, 32, 53, 54, 58, 59}
Other^†	(4) ^{2, 3, 20, 2}	(4) ^{18, 30, 57, 59}	(11) ^{15-17, 20, 26, 28, 29, 31, 32, 54, 55}
Prior utilization
Hospitalizations	(14) ^{12, 13, 22, 24-28, 30-32, 54, 58, 59}	(1) ²⁹	(10) ^{15-20, 23, 53, 55, 57}
ER visits	(4) ^{25, 29, 55, 57}	(1)²⁴	(17) ^{15-20, 22, 23, 26, 28, 30-32, 53, 54, 58, 59}
Clinic visits/Missed clinic visits	(3) ^{24, 25, 32}	(0)	(19) ^{15-20, 22, 23, 26, 28-31, 53-55, 57-59}
Index hospital length of stay	(4) ^{19, 21, 29, 31}	(3) ^{30, 53, 58}	(15) ^{15-18, 20, 22-24, 26, 28, 32, 54, 55, 57, 59}
Overall health and function
Functional status; ADL dependence; mobility	(2) ^{27, 57}	(6) ^{29-32, 58, 59}	(14) ^{15-20, 22-24, 26, 28, 53-55}
Self-rated health, quality of life	(3) ^{27, 31, 32}	(2) ^{28, 57}	(17) ^{15-20, 22-24, 26, 29, 30, 53-55, 58, 59}
Cognitive impairment	(7) ^{15-18, 28, 57, 59}	(5) ^{20, 31, 32, 54, 58}	(9) ^{19, 22-24, 26, 29, 30, 53, 55}
Visual or hearing impairment	(1) ²⁷	(1) ³²	(21) ^{15-20, 22-24, 26, 28-32, 53-55, 57-59}
Sociodemographic factors
Age	(19) ^{12-18, 20-23, 25-27, 32, 53, 54, 57, 59}	(7) ^{19, 24, 29-31, 55, 58}	(1) ²⁸
Gender	(15) ^{12-18, 20-26, 32}	(8) ^{19, 29-31, 53-55, 58}	(1) ²⁸
Race/ethnicity	(7) ^{12, 14, 19, 20, 22, 25, 26}	(8) ^{24, 30-32, 54, 55, 57, 58}	(8) ^{15-18, 23, 28, 29, 53}
*Social determinants of health*
SES/income/employment status	(5) ^{12, 14, 24, 25, 54}	(7) ^{20, 26, 31, 32, 57-59}	(10) ^{15-19, 22, 23, 28, 29, 53}
Insurance status^‡	(6) ^{19, 20, 24, 27, 31, 53}	(1) ⁵⁷	(5) ^{30, 32, 55, 58, 59}
Education	(0)	(4) ^{28, 31, 32, 58}	(17) ^{15-20, 22-24, 26, 29, 30, 53-55, 57, 59}
Marital status/# of people in home	(4) ^{24, 28, 31, 59}	(6) ^{29, 32, 53, 54, 57, 58}	(11) ^{15-20, 22, 23, 26, 30, 55}
Caregiver availability, other social support	(2) ^{32, 57}	(1) ³¹	(19) ^{15-20, 22-24, 26, 28-30, 53-55, 57-59}
Access to care/rurality	(5) ^{19, 22, 31, 53, 54}	(2) ^{20, 29}	(14) ^{15-18, 23, 24, 26, 28, 30, 32, 55, 57-59}
Discharge location (home, NH)	(2) ^{19, 20}	(1) ⁵³	(18) ^{15-18, 22-24, 26, 28-32, 54, 55, 57-59}

Six studies did not report candidate variables and only reported the final model.^{12-14, 21, 25, 27}

^†

Examples include use of telemetry, shock, planned vs emergent index hospitalization, heart rate, ejection fraction.

^‡

This category is not relevant to studies of Medicare patients^{15-18, 23} and non-US studies.^{12, 13, 28, 29, 54}