Table 1.

Baseline characteristics of the original cohort

	Overall	Readmitted	Not readmitted
Characteristics	n = 905	n = 167	n = 738
Age (year) median (interquartile range)	76 (68–82)	74 (68–82)	76 (68–82)
Sex
Male	415 (46%)	71 (43%)	344 (46%)
Female	490 (54%)	96 (57%)	394 (53%)
Non-Hispanic white race	770 (85%)	152 (20%)	618 (84%)
Smoking status
Current smoker	194 (21%)	31 (16%)	163 (22%)
Former smoker	524 (58%)	89 (17%)	435 (59%)
Never smoker	187 (21%)	47 (25%)	140 (19%)
Comorbidities*
Cardiac diseases	561 (62%)	115 (21%)	446 (60%)
Central nervous system diseases	50 (6%)	11 (22%)	39 (5%)
Endocrine diseases	293 (32%)	45 (15%)	248 (34%)
Gastrointestinal diseases	246 (27%)	46 (19%)	200 (27%)
Hematologic diseases	130 (14%)	22 (17%)	108 (15%)
Musculoskeletal diseases	36 (4%)	10 (28%)	26 (4%)
Neoplasms	34 (4%)	3 (9%)	31 (4%)
Psychiatric diseases	270 (30%)	50 (19%)	220 (30%)
Respiratory diseases	275 (30%)	45 (16%)	230 (31%)
Other diseases	52 (6%)	10 (19%)	42 (6%)
Mechanical ventilation use during the index hospitalization	56 (6%)	13 (23%)	43 (6%)
Socioeconomic factors
Educational level
8th grade or less	157 (17%)	36 (23%)	121 (16%)
Some high school education	232 (26%)	46 (20%)	186 (25%)
High school graduate	491 (54%)	79 (16%)	412 (56%)
Not responded	25 (3%)	6 (24%)	19 (3%)
Marital status (currently married)	313 (35%)	52 (17%)	261 (35%)
Number of children
0	99 (11%)	22 (22%)	77 (10%)
1	317 (35%)	23 (17%)	294 (40%)
≥ 2	489 (54%)	122 (18%)	367 (50%)
Limitations on activities and social life	584 (65%)	108 (19%)	476 (64%)
Poverty (annual household income <$25,000)	531 (59%)	103 (19%)	428 (58%)
Living in metropolitan area	564 (62%)	97 (17%)	467 (63%)

* 38 chronic conditions (defined by the Centres for Medicare and Medicaid Services Readmission Measurements; Table S2) categorized into 10 categories according to the organ systems