Table 1.
Baseline Characteristics: DHI and Historical Control Groups.
| Characteristic | Total (N=1,064) | DHI (N=200) | Control (N=864) | P-Value |
|---|---|---|---|---|
| Patient Demographics | ||||
| Age, years, mean ± SD | 64.3 ± 13.9 | 59.2 ± 11.5 | 65.4 ± 14.1 | p<0.001 |
| Women, n (%) | 394 (37.0%) | 58 (29.0%) | 336 (38.9%) | p=0.009 |
| Race, n (%)* | p=0.25 | |||
| White | 698 (67.1%) | 137 (70.6%) | 561 (66.3%) | |
| Non-White | 342 (32.9%) | 57 (29.4%) | 285 (33.7%) | |
| Insurance status, n (%)† | p<0.001 | |||
| Private insurance/preferred provider organization/health maintenance organization | 458 (44.4%) | 110 (55.0%) | 348 (41.8%) | |
| Medicare | 490 (47.5%) | 62 (31.0%) | 428 (51.4%) | |
| Medicaid | 67 (6.5%) | 22 (11.0%) | 45 (5.4%) | |
| Self-pay | 17 (1.7%) | 6 (3.0%) | 11 (1.3%) | |
| Education, years, mean ± SD | 14.6 ± 3.6‡ | |||
| Married, n (%) | 476 (46.8%) | 117 (60.3%) | 359 (43.6%) | p<0.001 |
| Household income, median (IQR) | $70,000 (28,700)§ | |||
| Clinical Characteristics | ||||
| Body mass index, mean ± SD | 29.7 ± 7.9 | 30.6 ± 5.9 | 29.5 ± 8.2|| | p=0.07 |
| Smoking, n (%) | p=0.01 | |||
| Current Smoker | 250 (26.3%) | 57 (28.5%) | 193 (25.7%) | |
| Former Smoker | 337 (35.5%) | 53 (26.5%) | 284 (37.9%) | |
| Never Smoker | 363 (38.2%) | 90 (45.0%) | 273 (36.4%) | |
| Comorbidities, n (%) | ||||
| Hypertension | 772 (72.6%) | 136 (68.0%) | 636 (73.6%) | p=0.11 |
| Obesity | 252 (23.7%) | 60 (30.0%) | 192 (22.2%)# | p=0.02 |
| Diabetes, w/wo complications | 428 (40.2%) | 83 (41.5%) | 345 (39.9%) | p=0.68 |
| Congestive heart failure | 396 (37.2%) | 58 (29.0%) | 338 (39.1%) | p=0.008 |
| Pulmonary disease** | 225 (21.2%) | 25 (12.5%) | 200 (23.2%) | p=0.001 |
| Peripheral vascular disease | 146 (13.7%) | 9 (4.5%) | 137 (15.9%) | p<0.001 |
| Renal failure | 241 (22.7%) | 28 (14.0%) | 213 (24.7%) | p=0.001 |
| Liver disease | 43 (4.0%) | 7 (3.5%) | 36 (4.2%) | p=0.67 |
| Cancer | 25 (2.4%) | 3 (1.5%) | 22 (2.6%) | p=0.38 |
| Depression | 143 (13.4%) | 19 (9.5%) | 124 (14.4%) | p=0.07 |
| Total comorbidity count, median (IQR)†† | 4 (3) | 3 (3) | 4 (4) | p<0.001 |
| 0–3 | 460 (44.1%) | 107 (54.9%) | 353 (41.6%) | p<0.001 |
| 3–5 | 325 (31.2%) | 59 (30.3%) | 266 (31.4%) | |
| ≥5 | 258 (24.7%) | 29 (14.9%) | 229 (27.0%) | |
| Hospitalization Characteristics | ||||
| Hospital, n (%) | p=0.91 | |||
| JHH | 541 (50.9%) | 104 (52.0%) | 437 (50.6%) | |
| JHBMC | 367 (34.5%) | 70 (35.0%) | 297 (34.4%) | |
| Massachusetts General | 84 (7.9%) | 14 (7.0%) | 70 (8.1%) | |
| Reading | 72 (6.8%) | 12 (6.0%) | 60 (6.9%) | |
| Type of MI, n (%) | p<0.001 | |||
| NSTEMI | 797 (74.9%) | 121 (60.5%) | 676 (78.2%) | |
| STEMI | 267 (25.1%) | 79 (39.5%) | 188 (21.8%) | |
| Intervention (during index admission), n (%) | p<0.001 | |||
| Percutaneous coronary intervention alone | 451 (42.4%) | 131 (65.5%) | 320 (37.0%) | |
| Coronary artery bypass grafting surgery alone | 178 (16.7%) | 44 (22.0%) | 134 (15.5%) | |
| Both | 12 (1.1%) | 8 (4.0%) | 4 (0.5%) | |
| Neither | 423 (39.8%) | 17 (8.5%) | 406 (47.0%) | |
| Length of stay, days, median (IQR) | 4 (6) | 5 (7) | 4(7) | p=0.03 |
| Discharge disposition, n (%) | p<0.001 | |||
| Home | 722 (67.9%) | 167 (83.5%) | 555 (64.2%) | |
| Home care | 200 (18.8%) | 18 (9%) | 182 (21.1%) | |
| Skilled nursing facility | 45 (4.2%) | 1 (0.5%) | 44 (5.1%) | |
| Rehabilitation | 34 (3.2%) | 12 (6.0%) | 22 (2.6%) | |
| Hospice/other hospital | 48 (4.5%) | 2 (1%) | 46 (5.3%) | |
| AMA/shelters/police custody/unknown | 15 (1.4%) | 0 (0.0%) | 15 (1.7%) | |
DHI: digital health intervention; SD: standard deviation; IQR: interquartile range; JHH: Johns
Hopkins Hospital; JHBMC: Johns Hopkins Bayview Medical Center; MI: myocardial infarction;
NSTEMI: non-ST-elevation myocardial infarction; STEMI: ST-elevation myocardial infarction;
AMA: against medical advice
Both the DHI and control groups had patients with unknown race classified as missing
Primary payer; Insurance of “Workers compensation/unknown” considered as missing
31% missing data for formal education in the DHI group
Only 91 of Corrie group patients provided valid values
26.6% missing body mass index data for control group
3.6% missing history of obesity data for control group
Pulmonary circulation disorders and chronic pulmonary disease
Unweighted, Agency for Healthcare Research and Quality Elixhauser comorbidity count includes 29 comorbidities (no imputation for missing values): congestive heart failure, valvular disease, pulmonary circulation disease, peripheral vascular disease, hypertension, paralysis, other neurological disorders, chronic pulmonary disease, diabetes with chronic complications, diabetes without chronic complications, hypothyroidism, renal failure, liver disease, chronic peptic ulcer disease, HIV and AIDS, lymphoma, metastatic cancer, solid tumor without metastasis, rheumatoid arthritis/collagen vascular diseases, coagulation deficiency, obesity, weight loss, fluid and electrolyte disorders, chronic blood loss anemia, deficiency anemias, alcohol abuse, drug abuse, psychoses, and depression P value: Univariate analyses using chi-square and fisher exact tests for binary and categorical variables and independent t-tests for continuous variables or Mann-Whitney test for medians were performed to determine whether there were differences in patient characteristics between DHI and control groups