Factors Associated With Use of Cardiopulmonary Resuscitation in Seriously Ill Hospitalized Adults FREE

Initially designed to rescue patients experiencing a sudden cardiac arrest due to arrhythmia,¹ cardiopulmonary resuscitation (CPR) has come to be seen as a procedure that should be used for patients for whom there is reasonable chance of restoring cardiopulmonary function and prolonging life.² Many guidelines, articles, and legal actions recommend circumstances under which resuscitation should be attempted.

The likelihood of survival after CPR has been shown to vary with age and disease.³ Decisions against attempting CPR may be a component of care plans that limit aggressiveness of care.⁴ Yet decisions about CPR may reflect generally held expectations about particular diseases and perceptions of the appropriateness of specific treatments, rather than actual prognoses.⁵ Do-not-resuscitate (DNR) orders are more common in patients with more functional compromise and with increased age and vary by diagnosis, sex, race, and location.⁶ In the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT), a study of seriously ill hospitalized patients, earlier DNR orders were associated with patient preferences to forego resuscitation, worse overall prognosis, and age older than 75 years.⁷ In intensive care units, DNR order rates have increased and rates of initiation of CPR have declined in the past decade.^8- 10 Surprisingly, patient preferences about life-extending treatment as reflected in living wills have not been shown to alter DNR decision making.^11- 12

SUPPORT and the Hospitalized Elderly Longitudinal Project (HELP) were designed to describe and improve decision making and outcomes of care for seriously ill or elderly hospitalized adults.¹³ In SUPPORT, all patients were hospitalized with 1 of 9 illnesses, severe enough to have a high risk of dying in the ensuing 6 months. In HELP, all patients were 80 years of age or older and were enrolled at the time of emergency hospital admissions. Many patients received life-prolonging interventions, and sometimes these interventions conflicted with patients' or surrogates' preferences for end-of-life care.¹⁴

In both SUPPORT and HELP, among patients who died or experienced successful CPR during their enrollment hospitalization, we examined the features of the patient, the physician, and the hospitalization to understand what factors were associated with resuscitation attempts among patients who experienced cardiopulmonary arrest. We expected that the likelihood of having CPR at the end of life would reflect patients' prognoses and preferences. We aimed to measure the strength of those associations and to assess the potential impact of other clinical and demographic factors.

The data collection methods used in SUPPORT have been reported previously.¹³ From June 1989 to June 1991 (phase I) and from January 1992 to January 1994 (phase II), SUPPORT enrolled patients 18 years of age or older who met specific severity criteria for 1 of 9 serious illnesses (nontraumatic coma, acute respiratory failure, multiple organ system failure with sepsis and multiple organ system failure with malignancy, chronic obstructive pulmonary disease, congestive heart failure [CHF], cirrhosis, metastatic colon cancer, or inoperable non–small cell lung cancer) who were admitted to 1 of 5 medical centers: Beth Israel Hospital, Boston, Mass; MetroHealth Medical Center, Cleveland, Ohio; Duke University Medical Center, Durham, NC; St Joseph's Hospital, Marshfield, Wis; and the University of California Medical Center at Los Angeles. Some patients were eligible for the study at the time of admission; others became eligible as their condition worsened while in an intensive care unit. Patients were excluded if they died or were discharged within 48 hours of study enrollment; were admitted with a planned discharge within 72 hours; did not speak English; or had the acquired immunodeficiency syndrome (AIDS), multiple trauma, or pregnancy. SUPPORT entry criteria and enrollment have been reported in detail elsewhere.¹⁵ In these analyses, we grouped patients with acute respiratory failure and patients with multiple organ system failure and sepsis together because our previous work had found them to be overlapping categories with similar prognoses and treatments.¹⁶

HELP enrolled patients 80 years of age and older, with any diagnosis except elective surgery, AIDS, or multiple trauma, who had an unplanned hospitalization for 48 hours or more at 1 of 4 teaching hospitals (Beth Israel Hospital, MetroHealth Medical Center, St Joseph's Hospital, and the University of California Medical Center at Los Angeles) between February and November 1994. Patients were assessed for eligibility for HELP at the time of hospital admission.

Institutional review committees at all participating hospitals approved the study. Informed consent was obtained prior to interviews.

The data collection methods used in HELP were identical to those in SUPPORT for the purposes of this analysis. The following descriptive variables were recorded from medical records: diagnoses including comorbid conditions,¹⁷ vital signs, common laboratory values, and a clinical assessment of neurological status using the Glasgow Coma Scale. We obtained the date of any attempt at CPR (documentation in the medical record of a call for the CPR team and their having initiated CPR) and the date of death from the record. Disease severity was assessed using the Acute Physiology, Age, Chronic Health Evaluation (APACHE) III Acute Physiology Score (APS).^13,18

Patients and their surrogate decisionmakers were interviewed in the first week of entry into SUPPORT or HELP. Interview data included demographic factors, perceived quality of life (using a 5-point scale), and functional status 2 weeks prior to admission using a modified Katz activity of daily living (ADL) scale ranging from 1 to 7 points.¹⁹ Patient interview data were available for 233 subjects; for 1486 subjects, the surrogate's response was calibrated to patients' responses and substituted as described previously.²⁰ When both patient and surrogate responses were unavailable, we imputed ADL (for 814 patients) and quality of life values (for 868 patients) using a logistic regression model adjusting for patients' interview status, diagnosis, age, coma score, APS, comorbidities, dementia, and sites.²⁰ When we restricted our analysis to patients without imputed data, our results were unchanged; therefore, we present models including imputed data as our primary analysis.

Preferences about resuscitation were assessed with the following question: "As you probably know, there are a number of things doctors can do to try to revive someone whose heart has stopped beating, which usually includes a machine to help breathing. Thinking of your current condition, what would you want your doctor to do if your heart ever stops beating?: (1) would want doctors to try to revive; (2) would want doctors not to try to revive; (3) would want CPR but no ventilator; and (4) ‘don't know'"(the last 2 responses were recorded if the patient or surrogate volunteered them). For our analyses, responses 1 and 3 were included as showing a preference for CPR. Patients who responded "don't know" were also considered as if they had stated a preference for CPR, as would be done in clinical practice. Surrogate response for patients' preferences about CPR were used for 1479 patients in this analysis who could not be interviewed; 601 patients died before their interview and 1584 patients were intubated, in coma, or otherwise unable to communicate. All surrogate interviews reported here were conducted prior to the patient's death. No data about preferences were available for 820 subjects (32.7%), either because a surrogate could not be identified or the patient or their surrogate declined to answer the question.

In a separate interview within 5 days of enrollment, but prior to patient death, the most senior physician available on the treatment team was asked to state the probability (0-100) that the patient would live for 2 months or more. Physician interview data were available for 1972 patients.

In this secondary analysis of SUPPORT and HELP data, we identified all patients in the SUPPORT and HELP studies who died during their index admission and/or received CPR during their enrollment hospitalization. We considered CPR to have been provided if we found chart documentation of CPR on or after the third day after study admission. Since patients were excluded from SUPPORT if death occurred during the first 48 hours of study enrollment, we excluded all CPR attempts tried on the first 2 calendar days of study entry.

Patients were characterized with descriptive statistics. To study the bivariable association between CPR attempts and patients' characteristics, we used χ² tests to analyze discrete variables and the Wilcoxon test for continuous variables. We used logistic regression models to determine which factors were associated with a CPR attempt at the time of cardiopulmonary arrest. Independent variables included in the model were patient age, race, sex, disease group, preferences for CPR, APS on day 3, number of ADL dependencies, patient reported quality of life, physician's estimate of patients' 2-month survival, and study site. We used the c statistic as a measure of the ability of the model to discriminate between those who did and those who did not receive a CPR attempt (0.5 = no discrimination, 1 = perfect discrimination).²¹ A 2-sided α of .05 was used as the criterion for significance. In a secondary analysis, we added to the model whether the patient had a DNR order prior to cardiopulmonary arrest to explore whether variation in DNR orders explained the variation in CPR we observed, but found that DNR orders were highly collinear with use of CPR, resulting in substantial increases in SEs and an unstable model. Separately, to assess whether secular trends confounded our results, we also adjusted for year of study entry and results were similar to our primary analyses.

SUPPORT and HELP enrolled 10,281 subjects. Of these, 2505 subjects experienced cardiopulmonary arrest, and 514 (21%) received CPR on or after the third study day during their index hospitalization. Of the 514 patients who received CPR, 93 (18.1%) survived the index hospitalization, and 327 (63.6%) had CPR attempted within the last 2 days of life (293 on the calendar day of death and 34 on the day before death). Table 1 shows the age, sex, race, primary diagnosis, APS on the third study day, ADL score, and quality of life 2 weeks prior to study entry, and the number of comorbidities for patients with and without an attempt at resuscitation. Patient or surrogate preference to attempt CPR was associated with having CPR, yet 13% of patients (or surrogates) who received CPR preferred to forego CPR, and 38% of patients who wanted CPR or were unsure did not receive CPR at the end of life. Patients who had CPR were younger, more often African American, and more often male. We found substantial variation by site and diagnosis. Patients with fewer ADL dependencies and better APS were more likely to receive a CPR attempt.

Of the 514 patients who received CPR on or after day 3 of the study entry, 15 (3%) had DNR orders written on or before the day prior to the CPR attempt, and 50 had DNR orders written on the day of the attempt, while 449 had no DNR orders written. Of the 93 patients who survived CPR, 1 had a DNR order written the day of the CPR attempt, 8 had DNR orders written subsequently, and 1 had a DNR order prior to the CPR attempt. Of the 421 patients who had CPR but died during the index hospitalization, 293 died on the same day of the last CPR attempt, and 128 lived more than 1 day after the last CPR attempt. Among the 293 patients who died on the same day of the last CPR attempt, 29 had DNR orders written that day. Among the 128 who lived more than 1 day after the last CPR attempt, 93 had DNR orders written before death.

Of the 1991 patients who died without CPR attempts, 1802 (91%) had DNR orders in place. Of the 189 patients who died without DNR orders or a CPR attempt, 75 had DNR decisions documented in the medical record without a specific DNR order. Among the 114 remaining patients who died without a CPR attempt prior to death or a DNR order or note, 42 had preferred CPR, 24 had preferred to forego CPR, 9 were unsure, and 39 had no data available.

Of the 514 patients who had CPR, 74 (14%) had more than 1 CPR attempt during the hospitalization. Of the 421 patients who had CPR but died during the index hospitalization, 62 (15%) had more than 1 CPR attempt. Of the 93 patients who had CPR and survived the hospitalization, 12 (13%) had more than 1 CPR attempt.

Table 2 shows the adjusted odds ratios (ORs) for the factors that were significant in the logistic regression model. The multivariable model shows that the adjusted likelihood of a resuscitative attempt decreased with increasing age. Men were more likely to have an attempt at resuscitation than were women. African Americans were more likely to undergo a CPR attempt. Patients who expressed clear preference against CPR were less likely to undergo CPR than those who had no preference or who wanted CPR. Patients who reported better quality of life prior to hospitalization were more likely to receive CPR. Neither APS nor functional status were associated with the use of CPR.

Patients with CHF were most likely to receive CPR. Patients in coma were least likely to have a resuscitative effort. Use of CPR varied substantially across sites. For patients at one site, the OR for having CPR was 2.53 compared with patients at another study institution. Physician prognostic estimates were strongly associated with receiving CPR; the OR for having CPR increased by 0.14 for each 10% increase in the likelihood of survival at 2 months. The c statistic for our multivariable model is 0.746.

Resuscitation was attempted for 514 (21%) of the 2505 patients who experienced cardiac arrest during their index hospitalization and 93 (18%) of 514 patients who had CPR survived their index hospitalization. Most patients who died more than 1 day following a CPR attempt had a DNR order written prior to death. We found that the likelihood of attempting resuscitation at the time of cardiac or pulmonary arrest varies substantially with prognosis and preferences, quality of life, diagnosis, site of hospitalization, and patient age, sex, and race.

Most medical ethicists suggest that decisions about resuscitation should be guided by patient preferences and by the likelihood of success of the resuscitative effort or the patient's prognosis for survival. In our study, the physician estimate of 2-month survival and patient preference have an important effect on use of CPR, but are similar in magnitude to other variables. Although less than 60% of patients who had DNR orders died during their initial hospitalization in SUPPORT,⁷ similar factors were associated with the timing of DNR orders among all patients in SUPPORT and the use of CPR among patients experiencing cardiopulmonary arrest. Previous work in SUPPORT identified a strong association between patient preferences and DNR orders,⁷ and in our study, patients with a DNR order generally did not receive an attempt at resuscitation at the end of life. Although there was a strong correlation between preferences, DNR orders, and use of CPR, 9% of patients who died without CPR did not have a DNR order in place. Of the 114 patients who died without a CPR attempt, DNR order or note, 42 patients or their surrogates had expressed a preference for CPR.

Patients for whom we had no data about preferences had a rate of CPR attempt similar to those who preferred CPR. Many of these subjects lacked a ready surrogate who might have made health care decisions to limit interventions. Of patients or surrogates who wanted CPR or were unsure, only 28% received CPR, while 11% of patients who did not want CPR received an attempt at CPR. This lack of congruency between preferences and treatment may reflect changes in preferences or prognoses in the time between interviews and cardiopulmonary arrest or misunderstood communication between patients and physicians. Physician decisions about CPR may be heavily influenced by factors such as their own values and preferences.^22- 23 Some clinical situations may appear to offer so little hope of effectiveness of CPR that physicians may not offer an attempt at CPR to patients or surrogates. In other work, patient preferences were not associated with the use of life-sustaining treatment.²⁴

Our data show higher rates of CPR attempts for patients for whom physicians felt there was reasonable likelihood of surviving 2 months. In a recent study of intensive care unit patients, severity of illness (APACHE III score) was the most important variable associated with a DNR order.²⁵ Conversely, when death is not expected imminently, physicians may be reluctant to forego resuscitation. However, even in end-stage disease, physicians may have difficulty recognizing that death is imminent.^26- 27

It may seem that decisions to forego an attempt at CPR should not vary with the type of disease after adjustment for physician estimate of prognosis. However, characteristics associated with disease type may explain different patterns of attempted resuscitation. For example, reasonably well-defined prognostic markers are available for patients with incurable, metastatic cancer or with coma, and when poor prognosis is clear, many physicians and patients avoid CPR. In fact, some question the merits of making CPR available to terminally ill cancer patients.^28- 29

However, for patients with other diseases, the prognosis may be more uncertain. Patients with end-stage CHF follow a less predictable course,^26,30 and this diagnosis may be a more important influence on the decision to attempt CPR than the survival prognosis itself. Furthermore, despite a poor long-term prognosis, patients with advanced CHF may be quickly resuscitated from an event caused by a cardiac arrhythmia. Physicians may also have different thresholds of perceived chance of survival of patients for recommending CPR for patients with CHF or chronic obstructive pulmonary disease compared with those with cancer.³¹ The ambiguity in prognosis for CHF and the ability of patients with CHF to respond well to treatment even late in the course may explain the increased use of CPR for patients with CHF compared with patients with other diseases included in our study.

The patients who received resuscitation attempts did not significantly differ in severity of illness (as measured by APS) on the third study day or in functional status 2 weeks earlier, in the adjusted analysis, when compared with those who did not have a resuscitation attempt. This contrasts with other reports in which more functionally dependent patients received less aggressive care than others. However, our measure for functional status may be inaccurate, in part, because it was imputed (rather than reported directly by patient or surrogate) for one third of our subjects. Alternatively, for the seriously ill patients included in SUPPORT, there may have been less variation in functional status compared with those described in other studies. Additionally, the strong correlation between prognostic estimate and measures of disease severity may have dampened any possible effect of functional status and APS on use of CPR in our multivariable model. In contrast to our findings on functional status, we found that patients were more likely to receive CPR if they reported better quality of life prior to hospitalization.

Several studies suggest that hospitalized older persons who are seriously ill have similar rates of short- and long-term success of resuscitation attempts compared with younger patients.^32- 33 Long-term survival and functional status were worse after successful CPR for individuals older than 70 years in another study.³⁴ In our study, older patients were less likely to receive CPR, even after adjustment for patient preferences and severity of illness. This observation is consistent with other observations that suggest that less aggressive care is provided to older patients.³⁵ Less aggressive care for older persons may reflect patient and physician values.^36- 37 Other analyses of SUPPORT data found that older seriously ill patients preferred CPR less often than did younger patients.³⁸ While differing preferences are not sufficient to explain the effect we document, older persons or their families may be more readily persuaded to avoid CPR as their clinical situation worsens.

African American patients had higher rates of attempts at CPR than non–African Americans, even after adjustments for their greater preference for CPR. Differing priorities in end-of-life care have previously been observed between various cultural and racial groups,^39- 40 but it is unclear what effects these differences have on decisions to attempt CPR at the end of life.

Variation in rates of attempted resuscitation by site suggests that decisions to attempt resuscitation are influenced by the culture of local medical practices. The influence of the institution on the likelihood of attempting CPR was more powerful than patients' preferences, which is difficult to justify. Profound geographic variation in care for the dying has been demonstrated in other work.^41- 42 Understanding how decisions about attempting resuscitation are made in different settings and what influences guide these decisions may help to identify ways to improve care for the seriously ill.

This study has several limitations. First, our analysis focuses on factors associated with use of CPR but because we restricted our analysis to the index hospitalization, our data cannot be used to estimate the longer-term survival of patients following CPR. Additionally, in our analysis, we do not account for variation in success of CPR in different patient populations or in different institutions, nor do we present data on factors associated with successful CPR. However, the likelihood of successful CPR is generally low in hospitalized patients, especially in those similar to patients in SUPPORT.^3,32- 33 Both SUPPORT and HELP were based in academic referral hospitals and may have attracted patients more likely to desire aggressive care. Limiting our description to those who had successful CPR or died during their initial hospitalization excludes information on outcomes experienced shortly after hospital discharge or in other settings. Since patients who died or were discharged within the first 48 hours of enrollment were excluded, our results do not generalize to patients' entire hospital stay. Since we did not collect data on the exact time DNR orders were written, we are unable to tell which occurred first when a CPR attempt and DNR order occurred the same day. However, it is likely that DNR orders were generally written after CPR attempts when they occurred on the same day.

Our reliance on surrogate responses and imputed interview data in both SUPPORT and HELP may introduce bias. Surrogates may not accurately understand or predict patients' preferences.⁴³ Yet in many clinical settings, surrogates function in a role of decision maker. Functional status data derived by imputing the number of functional deficits from a logistic regression model may reduce our ability to find differences in functional status among patient groups. Finally, our analysis uses data from SUPPORT and HELP collected from 1989 to 1994. Practice patterns regarding CPR and end-of-life care for seriously ill patients may have changed since these data were collected.

We found that a CPR attempt was associated with patient or surrogate preferences for CPR and the physician's estimate of better survival at 2 months. However, the size of these effects is modest and comparable to the effect of other factors. The variation in use of CPR across different diagnoses may be explained by variability in the clinical course of disease and prognostic uncertainty. Patients' race, sex, age, and site of hospitalization, however, had significant effects that are more difficult to explain. Future work to improve CPR decision making should include perceptions of CPR effectiveness and seek to understand cultural forces in medical and lay communities that cause the variations we observed. Additionally, systems to ensure that patients' preferences are addressed and that DNR orders are written and followed need further attention and improvement.