Recent attention has been given to the prevalence of caregiving among patients with chronic conditions in the United States.1 It is estimated that, annually, 65 million caregivers provide care to persons with disabilities and chronic illness, including cardiovascular disease (CVD).1 Chronic conditions, such as diabetes and heart failure, are associated with longer length of stay and readmission among patients who undergo cardiac surgery.2–4 Patients who undergo surgery with and without chronic conditions may receive assistance with medical and personal needs from paid or informal (unpaid) caregivers, such as family members or friends, before and during their hospital stay.1,5 The relation between having a caregiver and cardiac surgery outcomes is not established and may be confounded by a greater prevalence of comorbid conditions among those with caregivers. Past study of outcomes in cardiac patients with caregivers has largely been limited to studies in nonsurgical populations,6–9 those that examined nonclinical (eg, psychosocial) patient outcomes,10–12 those that did not have a referent group,13 and/or those that focused on outcomes in the caregiver but not in the patient.14–18 Assessment of caregiver status may have the potential to identify patients who undergo cardiac surgery and who are at risk for adverse clinical outcomes and prolonged length of stay.
Strategies to identify patients at risk for adverse outcomes before cardiac surgery are needed so that appropriate preventive interventions and resources can be targeted.19,20 Predictive risk models designed to identify patients who undergo cardiac surgery and who are at increased risk for poor postoperative outcomes are available but may be perceived as time consuming or too cumbersome to use in a clinical setting.21 Moreover, predictive risk models may include a large number of parameters as well as variables that may not be immediately available preoperatively.22 Systematic identification of patients who undergo cardiac surgery and who are at risk for adverse clinical outcomes is an important initial step in developing interventions aimed to reduce postoperative length of stay, rehospitalization, or death. The purpose of this study was to examine the association between having a caregiver and clinical outcomes (length of postoperative hospital stay and rehospitalization or death at 1 year) among patients who underwent cardiac surgery, independent of traditionally collected demographic and clinical information.
The study participants were 665 patients consecutively admitted for surgery to the CVD service at New York-Presbyterian Hospital/Columbia University Medical Center who took part in the Family Cardiac Caregiver Investigation To Evaluate Outcomes Study sponsored by the National Heart, Lung, and Blood Institute. Family Cardiac Caregiver Investigation To Evaluate Outcomes was a prospective observational study designed to evaluate the association between having a caregiver and clinical outcomes of patients hospitalized for CVD under medical and surgical care. Enrollment began in November 2009, and 1-year follow-up was completed in September 2011. Consecutive patient participant recruitment was achieved through daily systematic review of hospital admission logs to identify new admissions to the CVD service. Patients were included if they underwent cardiac surgery during their admission and were excluded from participation if they were unable to read or understand English or Spanish, lived in a full-time nursing facility, were unable to participate because of mental status, or refused to complete the survey. Trained bilingual research staff distributed the surveys in English and Spanish to potential participants to assess whether they had a caregiver in the past year and the extent of caregiving they received. Hospital logs were checked weekly for quality purposes to ensure that consecutive patients had been identified and approached for enrollment. If uncollected surveys were noted, the research staff attempted to contact the patient before discharge, or, if this was not feasible, the survey was mailed with a prestamped return envelope for the patient to complete and return. The overall enrollment rate was 93%. The study was approved by the Institutional Review Board of Columbia University Medical Center.
A caregiver was defined as a paid professional or a nonpaid (informal) person (eg, a family member or a friend) who assists the patient with medical and/or preventive care.5 The definition of caregiving was adopted from the AARP.23 The patients were asked whether they had a caregiver in the past year leading up to hospitalization and categorized themselves as having (1) a paid caregiver, (2) an informal caregiver, (3) both a paid caregiver and an informal caregiver, or (4) no caregiver. Those who had both a paid caregiver and an informal caregiver (n = 13) were classified as having a paid caregiver in the analysis because this did not materially alter the results.
The extent of caregiving provided to the participants was systematically assessed on the basis of the specific tasks defined using basic activities of daily living (eg, assistance with dressing, bathing) and instrumental activities of daily living (eg, assistance with meal preparation, transportation). The extent of caregiving was categorized as (1) extensive (patient has a paid caregiver or an informal caregiver who provides assistance with basic activities of daily living only or basic activities of daily living plus instrumental activities of daily living) or (2) nonextensive (patient has an informal caregiver who provides assistance with instrumental activities of daily living or less or has no caregiver).
Postoperative length of hospital stay was defined as the number of days between the first surgical procedure and discharge and was calculated by subtracting the surgical procedure date from the discharge date. All-cause rehospitalization was systematically collected by hospital electronic clinical information system, which is updated daily. To supplement the outcome data collected by the clinical system, all participants who underwent cardiac surgery were systematically contacted via mail or telephone 1 year after the index hospitalization that corresponded to their baseline survey date and were queried regarding rehospitalization in the past year (86% response rate). Rehospitalization was defined as rehospitalization at New York-Presbyterian Hospital or elsewhere. The analyses using this definition were similar to the analyses limited to readmission to New York-Presbyterian Hospital only. Vital status was obtained via hospital clinical information system, which is updated monthly with National Death Index data.
Demographic characteristics (ie, age, gender, race/ethnicity, marital status, and health insurance status), medical history (including diabetes mellitus, renal disease, myocardial infarction, stroke, peripheral vascular disease, heart failure, and chronic obstructive pulmonary disease), current smoking status, baseline anthropometric data, and postoperative hemodynamic status were documented by standardized electronic chart review conducted by Health Insurance Portability and Accountability Act trained research staff. Current and previous medical conditions were determined using International Classification of Diseases, Ninth Revision, billing codes and physician or nurse practitioner notes. Type of surgery (ie, coronary artery bypass graft [CABG] versus no CABG, valve/other) was defined using congenital and acquired cardiac procedure codes from New York State Department of Health Division of Quality and Patient Safety Cardiac Services Program.
The surveys were created and processed using the intelligent character recognition software EzDataPro32 (version 8.0.7; Creative ICR, Inc, Beaverton, Oregon) and ImageFormula (version Dr-2580C; Canon U.S.A., Inc, New York, New York). The data were double-checked for errors and stored in a Microsoft Access database. Descriptive statistics are presented as frequencies and percentages. Postoperative length of stay was dichotomized at more than 7 days versus 7 days or less on the basis of the national survey data documenting approximately 7 days as the mean postoperative length of stay for coronary artery bypass and valve procedures.3,24 Univariable associations between having a caregiver, demographic factors, and comorbidities with postoperative length of stay and rehospitalization or death at 1 year were evaluated using χ2 statistics. Multiple logistic regression models were used to evaluate the association between having a caregiver and outcomes adjusted for the categorical demographic and comorbid conditions listed and defined in Table 4. Because of the nonexperimental study design, propensity score weights were calculated and propensity score weighted logistic models were fitted to evaluate the potential role of exposure selection bias in observed associations; model covariates for propensity score weighted logistic models included age, race/ethnicity, gender, marital status, health insurance, myocardial infarction, heart failure, peripheral vascular disease, stroke, renal disease, chronic obstructive pulmonary disease, diabetes mellitus, postoperative hemodynamic status, and type of surgery.25 The analyses were completed using SAS software (version 9.2; SAS Institute, Cary, North Carolina). Statistical significance was set at P < 0.05.
The baseline participant characteristics are presented in Table 1. The prevalence of having a caregiver in the year before surgery of this population was 28%, with 8% of the participants (n = 54) reporting having a paid caregiver and 20% (n = 129) having only an informal caregiver.
Caregiving and Postoperative Length of Stay
Among the patients with a caregiver, 66% had a postoperative length of stay longer than 7 days compared with 51% among the patients without a caregiver. Having a caregiver (paid or informal) was significantly associated with postoperative length of stay longer than 7 days in univariate analysis (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.30–2.65). A gradient was observed for type of caregiver (paid versus informal versus none) and odds of a longer postoperative length of stay; the odds of a longer stay were highest among the patients with a paid caregiver versus no caregiver and among those who received extensive versus nonextensive caregiving (Table 2).
Age, marital status, and several comorbid conditions were significantly associated with postoperative length of stay more than 7 days including previous myocardial infarction, heart failure, peripheral vascular disease, renal disease, chronic obstructive pulmonary disease, diabetes mellitus, and unstable postoperative hemodynamic status or shock (Table 3). The association between having a caregiver and longer postoperative length of stay remained significant in the propensity score weighted analysis (OR, 1.76; 95% CI, 1.19–2.60). In multivariable analysis adjusted for demographic and comorbid conditions, the association between having a caregiver and longer postoperative length of stay was attenuated but retained significance among the patients with paid caregivers versus none (Table 4).
Caregiving and Rehospitalization or Death at 1 Year
At 1 year, 264 participants had been rehospitalized and 26 had died (n = 9, rehospitalized and subsequently died within 1 year). Among the patients with a caregiver, 50% were rehospitalized or had died within 1 year compared with 39% among the patients without a caregiver. Having a caregiver (paid or informal) was associated with rehospitalization or death at 1 year in univariate analysis (OR, 1.57; 95% CI, 1.11–2.21). There was a gradient observed for having a paid versus informal versus no caregiver and risk of rehospitalization or death at 1 year; the patients who received extensive versus nonextensive caregiving were more likely to be rehospitalized or dead at 1 year (Table 2). The propensity score weighted analysis of the association between having a caregiver and rehospitalization or death at 1 year was not significant (OR, 1.22; 95% CI, 0.83–1.81). The association between having a caregiver and rehospitalization or death at 1 year did not retain statistical significance after multivariable adjustment (Table 4).
In this prospective study of having a caregiver and clinical outcomes among patients who underwent cardiac surgery, we documented a significant association between having a caregiver in the year before surgery and longer postoperative length of stay and rehospitalization or death at 1 year. Having a paid caregiver was independently associated with longer postoperative length of stay after adjustment for confounders and comorbidities. There was a significant association between having a caregiver and rehospitalization or death at 1 year, which was attenuated after adjustment for demographic variables and comorbid conditions. These data suggest that systematic assessment of preoperative caregiver status may be a simple way to identify patients at risk for longer postoperative length of stay; preoperative caregiver status may also identify those at increased risk for rehospitalization or death at 1 year in the absence of measures for other predictive factors.
This study filled several gaps in the current literature by documenting a link between having a caregiver (versus no caregiver) and clinical outcomes among patients who underwent cardiac surgery. Before this study, most research related to outcomes in patients with cardiac disease with caregivers had been limited to studies in nonsurgical populations, those that examined nonclinical patient outcomes, and/or those that focused on outcomes in the caregiver but not in the patient.6–18
Recent work conducted in a variety of clinical settings has shown that comorbidity data, in conjunction with clinical data, significantly increased the performance of length of stay and mortality prediction models.26,27 Demographic and comorbid conditions associated with longer postoperative length of stay or rehospitalization or death in patients who underwent cardiac surgery in this study were consistent with those reported by others including older age, female gender, diabetes mellitus, heart failure, renal failure, chronic obstructive pulmonary disease, and history of peripheral vascular disease.2,3,28–32 The data from our study add to previous research, and, to our knowledge, these findings are the first to document a link between having a caregiver and clinical outcomes among patients who underwent cardiac surgery.
The association between having a caregiver and rehospitalization or death at 1 year in this study is similar to what was observed for patients who did not undergo surgery in our previous work33 and extends the finding to postoperative length of stay. The observed gradient for paid versus informal versus no caregiver was also similar.33 Adjustment for demographic variables and comorbid conditions explains much of the association with clinical outcomes for both patients who underwent surgery and those who did not, but the link between having a paid caregiver and postoperative length of stay among patients who underwent surgery is not fully explained by adjustment of measured confounders.
Unmeasured factors that predict postoperative length of stay that are not traditionally collected as part of routine clinical assessment may be captured by paid caregiver status, and residual confounding may have contributed to the observed association. For example, psychosocial factors such as depression and social isolation, and social factors such as disposition after discharge, were not measured in this study. These were not included in included in the propensity analysis and may be linked to longer length of stay and to having a paid caregiver.34,35 Similarly, data regarding patient income or financial status beyond health insurance type were not available, limiting our ability to assess the role of financial or socioeconomic status as a potential confounder.
There are other limitations to this study to consider in the interpretation of the results. Caregiver status was self-reported, and there may have been a misclassification; however, assessment was unlikely to be differential with respect to outcomes, and nonsystematic error would have reduced our ability to observe an association. In addition, the gradient observed for the association for having a paid, informal, and no caregiver and for extensive versus nonextensive caregiving supports that the definitions are robust. Outcomes measurement for rehospitalization at other hospitals was obtained through self-report; however, the response rate was high and nondifferential with respect to caregiver status. Multiple tests of association were conducted for this research, and some observed associations could have been due to chance; the consistency of the associations between comorbid conditions and clinical outcomes with other studies suggests that the results are unlikely to be artifact. Severity of each comorbid condition was not adjusted for in the multivariable analysis. This was a single-center study, which may limit translation of the results to other settings; however, the patient population was diverse and greater than 90% of the consecutively admitted patients who participated, which increases potential generalizability of results.
Our finding among the patients who underwent cardiac surgery that having a paid caregiver was associated with postoperative length of stay after adjustment for comorbidities suggests that it may be a simple marker that adds predictive value to traditionally collected clinical information. This result may have important policy implications, especially for reimbursement for length of stay. Caregiver status assessment may add value to risk-adjusted models that predict postoperative length of stay or rehospitalization or death. Systematic assessment of caregiver status may identify patients to target for social or preventive interventions aimed to reduce postoperative length of stay and healthcare costs. Future research should evaluate the incremental value of adding caregiver status to risk prediction models, as well as address the potential for interventions targeted at patients with caregivers to reduce postoperative length of stay and improve quality outcomes.
What’s New and Important
- Among patients hospitalized for cardiac surgery, having a self-identified caregiver was a significant independent predictor of prolonged (>7 days) postoperative length of stay, and those with paid caregivers were 3 times more likely to have an increased length of stay.
- Compared with patients without a caregiver, the odds of rehospitalization or death at 1 year were significantly higher among patients who underwent cardiac surgery with a caregiver, which was explained by greater comorbid conditions in multivariable models adjusted for confounders.
- These data suggest that caregiver status assessment at the time of hospitalization may be a simple method to identify patients who underwent cardiac surgery at risk for adverse clinical outcomes.
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Keywords:© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
cardiac surgery; caregiver; outcomes; prevention