Considerable attention has been devoted to the effect of social support on patient outcomes after acute myocardial infarction (AMI). However, little is known about the relation between patient living arrangements and outcomes. Thus, we used data from PREMIER, a registry of patients hospitalized with AMI at 19 United States centers from 2003 through 2004, to assess the association of living alone with outcomes after AMI. Outcome measurements included 4-year mortality, 1-year readmission, and 1-year health status using the Seattle Angina Questionnaire (SAQ) and the Short Form-12 Physical Health Component scales. Patients who lived alone had higher crude 4-year mortality (21.8% vs 14.5%, p <0.001) but comparable rates of 1-year readmission (41.6% vs 38.3%, p = 0.79). Living alone was associated with lower unadjusted quality of life (mean SAQ −2.40, 95% confidence interval [CI] −4.44 to −0.35, p = 0.02) but had no impact on Short Form-12 Physical Health Component (−0.45, 95% CI −1.65 to 0.76, p = 0.47) compared to patients who did not live alone. After multivariable adjustment, patients who lived alone had a comparable risk of mortality (hazard ratio 1.35, 95% CI 0.94 to 1.93) and readmission (hazard ratio 0.99, 95% CI 0.76 to 1.28) as patients who lived with others. Mean quality-of-life scores remained lower in patients who lived alone (SAQ −2.91, 95% CI −5.56 to −0.26, p = 0.03). In conclusion, living alone may be associated with poorer angina-related quality of life 1 year after MI but is not associated with mortality, readmission, or other health status measurements after adjusting for other patient and treatment characteristics.
Considerable attention has been devoted to the effect of social support and living arrangements on patient outcomes after acute myocardial infarction (AMI). Although living alone has been associated with an increased risk of acute coronary syndrome in the general population, the relation between living alone and outcomes after AMI is not well understood. Although some studies have found a positive association between living alone and mortality after AMI, others have not. Furthermore, no studies have examined the impact of living alone on quality of life or functional status after AMI. The purpose of this study was to characterize the relation between living alone and outcomes after AMI including mortality, rehospitalization, and health status.
Methods
We used data from the Prospective Registry Evaluating Myocardial Infarction: Events and Recovery (PREMIER), a national prospective registry of patients hospitalized with AMI. Registry procedures and baseline data have been previously published. In brief, PREMIER enrolled 2,498 patients with MI from 19 United States centers from January 1, 2003 through June 28, 2004. To be eligible patients had to be ≥18 years of age, have an AMI confirmed by cardiac enzymes, and show supporting signs or symptoms of AMI in the form of prolonged ischemia or electrocardiographic ST-segment elevation changes. For these analyses, patients with missing information on living alone were also excluded (n = 53) as were patients who were not discharged to hospice, nursing facilities, acute care, nonacute hospitals, or had expired (n = 181).
Information on patient demographics, clinical presentation, and treatment were obtained from detailed chart abstractions and baseline interviews administered during the index hospitalization. As part of the interview, patients were asked about their living arrangements at home and categorized as living alone or with others. Patients also completed the Enhancing Recovery in Coronary Heart Disease Patients (ENRICHD) Social Support Instrument (ESSI), a 7-item self-report survey that assesses 4 domains of social support: emotional, instrumental, informational, and appraisal.
Outcome measurements included 4-year and 1-year mortalities, 1-year readmission, and 1-year changes in health status. Data on mortality was obtained through linkage of the Social Security Death Master File to patient identifiers including Social Security Number, name, and date of birth. Changes in health status were measured using the Seattle Angina Questionnaire (SAQ) and the Short Form-12 (SF-12). The SAQ is a 19-item self-administered questionnaire that assesses several domains of coronary artery disease on a scale of 0 to 100 including physical limitation, angina stability, angina frequency, treatment satisfaction, and angina-related quality of life. For this study, we focused on the quality-of-life component as an outcome. Unlike the SAQ, which measures disease-specific health status, the SF-12 evaluates general health status using Physical and Mental Component Scales. For the 2 scales, lower numbers indicate worse health status.
We compared baseline characteristics of patients who lived alone to those living with others using chi-square or Fisher’s exact tests for categorical variables and t tests for continuous variables. To evaluate the independent association of living alone with mortality, rehospitalization, and health status measurements, we used Cox proportional hazards regression and linear regression models to adjust for patient and clinical characteristics. Covariates for multivariable analyses were selected using a combination of clinical judgment and examining the association between these factors and living-alone status. Covariates included patient demographics (age, gender, race, body mass index, marital status, employment status, living location, pet ownership, medical care payer, usual source of care, financial barriers to health care use), medical history (hypertension, depression, previous AMI, chronic heart failure), clinical presentation and treatment (left ventricular systolic function, creatinine, receipt of angiotensin-converting enzyme inhibitor and β blockers at discharge), ESSI score, and baseline health status scores.
Results
Of the 2,264 patients with living arrangement data in our sample, 471 patients (20.8%) reported living alone. A larger percentage of patients who lived alone were women and unemployed compared to patients who lived with others ( Table 1 ). Patients living alone also tended to be older, to score lower on the ESSI, and to present with lower mean quality-of-life and physical functioning scores. The 2 groups were comparable in other clinical characteristics and treatment variables.
| Variable | Living Alone | p Value | |
|---|---|---|---|
| Yes (n = 471) | No (n = 1,793) | ||
| Age (years), mean ± SD | 62.7 ± 13.5 | 59.3 ± 12.3 | <0.001 |
| Women | 200 (42.5%) | 523 (29.2%) | <0.001 |
| Race | 0.004 | ||
| White | 321 (68.3%) | 1,354 (75.9%) | |
| Black | 129 (27.4%) | 344 (19.3%) | |
| Hispanic | 12 (2.6%) | 43 (2.4%) | |
| Asian | 2 (0.4%) | 5 (0.3%) | |
| Other | 6 (1.3%) | 37 (2.1%) | |
| Marital status | <0.001 | ||
| Married | 51 (11.0%) | 1,301 (73.0%) | |
| Divorced | 145 (31.2%) | 162 (9.1%) | |
| Separated | 31 (6.7%) | 51 (2.9%) | |
| Widowed | 145 (31.2%) | 113 (6.3%) | |
| Single (never married) | 8 (18.1%) | 126 (7.1%) | |
| Common law | 6 (1.3%) | 23 (1.3%) | |
| Other | 3 (0.6%) | 5 (0.3%) | |
| Employment status | <0.001 | ||
| Full time | 130 (27.7%) | 713 (40.1%) | |
| Part time | 39 (8.3%) | 150 (8.4%) | |
| Unemployed | 301 (64.0%) | 916 (51.5%) | |
| Living location | <0.001 | ||
| Owned home | 229 (48.8%) | 1,351 (76.2%) | |
| Owned home or apartment | 199 (42.4%) | 264 (14.9%) | |
| Relative or friend’s home | 19 (4.1%) | 140 (7.9%) | |
| Nursing home or assisted living | 7 (1.5%) | 3 (0.2%) | |
| Homeless | 5 (1.1%) | 4 (0.2%) | |
| Other | 10 (2.1%) | 11 (0.6%) | |
| Pet ownership | 146 (31.1%) | 896 (50.1%) | <0.001 |
| Medical care payer | <0.001 | ||
| Commercial/preferred provider organization | 136 (30.2%) | 789 (45.8%) | |
| Health maintenance organization | 50 (11.1%) | 225 (13.1%) | |
| Medicare | 155 (34.4%) | 334 (19.4%) | |
| Medicaid | 32 (7.1%) | 93 (5.4%) | |
| None/self-pay | 54 (12.0%) | 214 (12.4%) | |
| Other | 24 (5.3%) | 67 (3.9%) | |
| Usual source of care | 0.002 | ||
| None | 57 (12.2%) | 191 (10.8%) | |
| Private doctor’s office | 211 (45.0%) | 869 (49.0%) | |
| Health maintenance organization or prepaid health plan | 30 (6.4%) | 139 (7.8%) | |
| Neighborhood clinic | 27 (5.8%) | 167 (9.4%) | |
| Hospital outpatient clinic | 121 (25.8%) | 358 (20.2%) | |
| Hospital emergency room | 14 (3.0%) | 21 (1.2%) | |
| Other | 7 (1.5%) | 25 (1.4%) | |
| Avoided acquiring health care because of cost | 108 (23.3%) | 304 (17.2%) | 0.003 |
| Body mass index (kg/m 2 ) | <0.001 | ||
| <18.5 | 11 (2.5%) | 20 (1.2%) | |
| 18.5–25 | 139 (31.7%) | 351 (20.5%) | |
| 25–30 | 147 (33.5%) | 629 (36.7%) | |
| 30–35 | 87 (19.8%) | 437 (25.5%) | |
| 35–40 | 41 (9.3%) | 165 (9.6%) | |
| >40 | 14 (3.2%) | 110 (6.4%) | |
| Smoker | 293 (62.2%) | 491 (27.4%) | 0.918 |
| Alcohol use | 0.248 | ||
| Never | 161 (71.6%) | 691 (71.3%) | |
| Less than monthly | 34 (15.1%) | 140 (14.4%) | |
| Monthly | 15 (6.7%) | 64 (6.6%) | |
| Weekly | 6 (2.7%) | 53 (5.5%) | |
| Daily | 9 (4.0%) | 21 (2.2%) | |
| Diabetes mellitus | 139 (29.5%) | 491 (27.4%) | 0.359 |
| Hypertension | 321 (68.2%) | 1,100 (61.3%) | 0.007 |
| Hypercholesterolemia | 220 (46.7%) | 908 (50.6%) | 0.129 |
| Congestive heart failure | 59 (12.5%) | 181 (10.1%) | 0.127 |
| Peripheral arterial disease | 34 (7.2%) | 127 (7.1%) | 0.919 |
| Previous myocardial infarction | 115 (24.4%) | 360 (20.1%) | 0.040 |
| Medication or counseling for depression | 78 (16.7%) | 207 (11.6%) | 0.004 |
| Clinical presentation and treatment | |||
| Myocardial infarction diagnosis | 0.586 | ||
| ST-elevation myocardial infarction | 199 (42.3%) | 801 (44.7%) | |
| Non–ST-elevation myocardial infarction | 270 (57.3%) | 980 (54.7%) | |
| Bundle-branch block/uncertain | 2 (0.4%) | 12 (0.7%) | |
| Killip class | <0.001 | ||
| I | 328 (79.0%) | 1,301 (86.4%) | |
| II | 73 (17.6%) | 152 (10.1%) | |
| III | 9 (2.2%) | 30 (2.0%) | |
| IV | 5 (1.2%) | 23 (1.5%) | |
| Left ventricular systolic dysfunction | 0.287 | ||
| Normal | 239 (50.7%) | 971 (54.3%) | |
| Mild | 99 (21.0%) | 390 (21.8%) | |
| Moderate | 82 (17.4%) | 263 (14.7%) | |
| Severe | 51 (10.8%) | 165 (9.2%) | |
| Creatinine (mg/dl), mean ± SD | 1.5 ± 1.9 | 1.4 ± 1.5 | 0.048 |
| Aspirin at arrival | 447 (97.4%) | 1,694 (96.6%) | 0.386 |
| β Blocker at arrival | 396 (92.7%) | 1,507 (91.7%) | 0.469 |
| Angiotensin-converting enzyme inhibitor for left ventricular systolic dysfunction at discharge | 105 (89.0%) | 313 (80.3%) | 0.030 |
| β Blocker at discharge | 418 (94.6%) | 1,576 (91.6%) | 0.036 |
| Baseline health status and social support measurements | |||
| ESSI score, mean ± SD | 20.4 (5.6%) | 22.7 (4.0%) | <0.001 |
| Seattle Angina Questionnaire quality of life, mean ± SD | 59.7 (24.4%) | 62.5 (23.2%) | 0.022 |
| Short Form-12 Physical Component Scale score, mean ± SD | 40.0 (12.9%) | 44.0 (12.2%) | <0.001 |
| Short Form-12 Mental Component Scale score, mean ± SD | 49.2 (12.4%) | 49.7 (11.4%) | 0.479 |
Patients who lived alone had higher unadjusted 1-year and 4-year mortalities but similar rates of 30-day mortality and 1-year readmission as patients who lived with others ( Table 2 ). Living alone was also associated with lower unadjusted quality of life adjusted for baseline scores and mental functioning but had no association with physical functioning compared to patients who did not live alone ( Table 3 ).
| Clinical Outcome | Living Alone (n = 471) | Not Living Alone (n = 1,793) | p Value |
|---|---|---|---|
| 30-day mortality | 6 (1.3%) | 19 (1.1%) | 0.697 |
| 1-year mortality | 37 (7.9%) | 96 (5.4%) | 0.039 |
| 4-year mortality | 102 (21.8%) | 256 (14.5%) | <0.001 |
| 1-year readmission | 161 (41.6%) | 606 (38.3%) | 0.792 |
| Health Status Measurement | Living Alone (n = 471) | Not Living Alone (n = 1,793) | Difference (living alone vs not living alone) | p Value |
|---|---|---|---|---|
| Mean (95% CI) | ||||
| Seattle Angina Questionnaire quality-of-life score, mean ± SE | 82.1 ± 1.1 | 84.5 ± 0.8 | −2.4 (−4.4 to −0.4) | 0.022 |
| Short Form-12 Physical Component Scale score, mean ± SE | 44.4 ± 0.7 | 44.8 ± 0.5 | −0.4 (−1.7 to 0.8) | 0.4676 |
| Short Form-12 Mental Component Scale score, mean ± SE | 52.0 ± 0.6 | 53.8 ± 0.4 | −1.7 (−2.8 to −0.7) | 0.0011 |
After adjustment for patient and clinical characteristics, there were no significant differences in mortality between those living alone and those living with others (4-year mortality hazard ratio 1.35, 95% confidence interval [CI] 0.94 to 1.93; Table 4 ). Mean quality-of-life scores remained slightly lower in patients who lived alone (SAQ −2.87, 95% CI −5.52 to −0.22, p = 0.03), whereas mean mental and physical functioning scores were comparable between groups (SF-12 Mental Component Scale −0.90, 95% CI −2.32 to 0.53, p = 0.22; SF-12 Physical Component Scale 1.04, 95% CI −0.58 to 2.66, p = 0.21; Table 5 ). Other variables associated with increased mortality and rehospitalization included female gender, living in a nursing home or assisted-living facility, hypertension, congestive heart failure, and presenting with an increased creatinine level ( Table 6 ). In contrast, homelessness, difficulty obtaining medical care, and receipt of depression medication or counseling were associated with worse health status measurements at 1 year.
