Cancer Economics

Incidence of Emergency Visits Among Oncology Patients Receiving Outpatient Chemotherapy: Implications for Care in a Capitated Market

Charles G. Martin, PhD; Kathryn F. Kennedy, LMSW-AP; Linda S. Elting, DrPH; Ellen Manzullo, MD, FACP; Carmen P. Escalante, MD, FACP; and Edward B. Rubenstein, MD, FACP
The University of Texas M.D.Anderson Cancer Center, Houston, Texas.

Introduction

The shift in providing medical care from the hospital setting to the outpatient setting has been fueled by diagnosis-related groups, technological advances, and changes in the healthcare environment as a consequence of managed care initiatives. It is estimated that 85% to 95% of cancer care occurs in the outpatient setting and that most chemotherapy treatments are administered outside the hospital in freestanding cancer centers, community oncology offices, comprehensive cancer centers, and ambulatory infusion suites.[1] All cancer patients are expected to receive treatment and care on an ambulatory basis at some point during the course of their treatment.[2]

Although patients receiving ambulatory chemotherapy may develop acute nausea and vomiting, most adverse events from chemotherapy occur days to weeks following treatment. In the future, the medical and financial responsibilities for these downstream events will likely become those of the provider. The number of cancer patients who will have an emergency event while receiving outpatient chemotherapy is not known, and risk factors for these events have not been examined systematically.

The increasing number of cancer diagnoses and the extent to which treatment is provided on an outpatient basis are factors that emphasize the importance of identifying subgroups of patients at high risk for subsequent emergency care. Therefore, a prospective study was conducted at our institution to estimate the incidence of emergency visits made by outpatients receiving scheduled chemotherapy and to identify risk factors associated with such visits.

Methods

Study Site

The University of Texas M. D. Anderson Cancer Center is a 518-bed, acute-care, comprehensive cancer center in Houston, Texas. During fiscal year 1992-1993, a total of 586,979 outpatient visits were reported.[3] During 1993, approximately 60,000 patients received chemotherapy on an outpatient basis.[4]

The Ambulatory Treatment Center at our center is a multidisciplinary unit that provides ambulatory hospital-based care, outpatient chemotherapy, and supportive care. This facility consists of a short-term infusion therapy unit (for treatments requiring less than two hours) and a long-term infusion therapy unit (for treatments requiring 24 hours or less). A 24-hour-per-day acute-care unit functions as the emergency room and is the focus of this report.

Selection of Patients

All patients included in the study fulfilled the following criteria: (1) They were officially registered patients, (2) they were currently receiving outpatient chemotherapy, (3) they had at least two outpatient chemotherapy appointments scheduled during the 90-day study period, (4) they had no procedures requiring a scheduled inpatient admission during the study period, and (5) they were at least 16 years of age.

Time at Risk

The Index Appointment was the first scheduled appointment, and the Follow-up Appointment was the second scheduled appointment during the 90-day period. The outcome measure - an emergency visit - was defined as an urgent, unplanned visit (ie, unscheduled outpatient services provided to patients whose conditions required immediate care). Time at risk for an emergency visit was defined as the number of days from the Index Appointment to the date of an emergency visit, date of hospitalization, date of death, or date of the Follow-up Appointment, whichever occurred first. No time-at-risk analysis was conducted for subsequent emergency visits.

Study Variables

The hospital is served by a clinical computing system that maintains information pertaining to resource scheduling, medical records, referral and census information, biographic and demographic data, employment and insurance information, and laboratory and pathology data. All data pertaining to this study were retrieved through this system. Twenty randomly selected medical records were reviewed, with an accuracy rate of 100%.

Demographic variables included age at Index Appointment and the patient's gender. Race was categorized as American Indian, Asian, black, Hispanic white, and non-Hispanic white. Clinical variables included the type and site of cancer, as well as the length of time from registration to the Index Appointment. Diagnostic categories, based on ICD9-CM codes,[5] were either grouped according to disease-site clinics or combined where multiple diagnoses were treated in a given clinic area.

Analysis

The incidence rate of one or more emergency visits was analyzed in relation to the demographic and clinical variables examined in this study. Proportional hazards regression analyses were used to investigate factors associated with the risk of an emergency visit.[6,7] These models were used to derive rate ratios (the ratio of the rate of an emergency event in patients with a given factor to that in patients without the factor). Rate ratios greater than 1.0 suggest an increased risk for an emergency visit, whereas rates less than 1.0 suggest a protective factor (ie, a reduced risk).

Each prognostic factor was examined univariately. A multivariate model was then used to evaluate the effect of each factor separately on the rate of an emergency visit. This model reflected the increased or decreased risk of an emergency visit based on each independent variable (prognostic factor) under investigation.

Results

The demographic and clinical characteristics of the study population are shown in Table 1. Of the 1,283 patients, 70% were between 40 and 69 years of age, 56% were women, and 76% were non-Hispanic white patients. Patients diagnosed with breast cancer (24%) and gastrointestinal or genitourinary cancer (19%) predominated. Length of time from registration to the Index Appointment ranged from less than one month to 36 years. Approximately 40% of the study population had been registered less than four months, and 44% had been registered longer than six months.

The mean (± standard deviation) length of time at risk was 27.6 ± 7.6 days for the 1,238 patients who had no emergency visits compared with 24.1 ±19.6 days for the 45 patients who had an emergency visit (P=.19). Of these 45 patients, 10 (22%) had a second emergency visit, three (7%) had a third visit, and two (4%) had a fourth visit during the study period.

As shown in Table 2, the overall incidence rate of an emergency visit was 10 visits per 100 patients per month (10/100/month). Patients 30 to 39 years of age had the highest rate of emergency visits (18/100/month), whereas patients older than 69 years of age had the lowest rate (5/100/month) (P<.05). A higher incidence rate of emergency visits was also found for patients diagnosed with melanoma (32/100/month) compared with 6/100/month for patients diagnosed with cancer from an unknown primary (P<.05) or with breast cancer (P=.12). The lowest incidence rate was found for those diagnosed with leukemia (3/100/month). The incidence of emergency visits was inversely associated with the length of time registered at the hospital. Emergency visits were 29/100/month for patients registered less than one month. This rate decreased to 6/100/month for patients who were registered longer than 12 months (P<.01).

Presenting problems and disposition of patients who had emergency visits are shown in Table 3. Fever (27% of patients) was the most common reason for the first emergency visit, followed by pain (18%), nausea (18%), weakness (9%), and other reasons (9%). This last category consisted of two patients who presented with headache and two who presented with abdominal pain. The distribution of problems resulting in subsequent emergency visits approximated those of the initial visit. Reasons for a second emergency visit were fever (30%), pain (20%), and nausea (20%).Presenting problems that resulted in a third and/or fourth emergency visit included fever, pain, nausea, bleeding, and other reasons, with each category representing 20%.

Most patients (71%) were discharged after the initial emergency visit; this figure decreased to 60% after the second emergency visit. The frequency of hospitalization following the emergency visit, however, increased with each subsequent emergency visit (27%, 30%, 40%, and 40% following the first, second, third, and fourth visits, respectively).

Prognostic Factors

Prognostic factors were examined separately, with emergency visits as the outcome measure in the proportional hazards models (Table 4). Univariately, an increased incidence of subsequent emergency visits was significantly associated with a diagnosis of melanoma or a diagnosis of lymphoma, Hodgkin's disease, or myeloma (P<.01). The rate of emergency visits, however, decreased significantly for patients registered three months or longer (P<.01). Age, sex, and race were not univariate predictors.

The results presented in the multivariate model included all prognostic factors in the study, using selected categories to compare the remaining groups for each variable. The referent categories included patients less than 30 years of age compared with those 30 years of age or older, women compared with men, non-Hispanic white race compared with all other races, breast cancer patients compared with other cancer patients, and patients registered for less than one month compared with those registered one month or longer.

Patients diagnosed with melanoma, as well as those with lymphoma, Hodgkin's disease, or myeloma, were four times more likely to have an emergency visit (P<.05) than were breast cancer patients. In addition, emergency visits were less likely to be reported by patients registered seven to 12 months or by those registered longer than 12 months (P<.01). Age, sex, and race were not significant predictors of emergency events in the multivariate model, although at least one emergency visit was three times as likely as younger patients for those 30 to 39 years of age and twice as likely for those 50 to 59 years of age.

Prognosis According to Prior Emergency and Subsequent Visits

Patients who had an emergency visit 30 days prior to the Index Appointment (n=47) were four times more likely to have an emergency visit during the study period (P<.01). Emergency visits that occurred more than 90 days prior to the Index Appointment, however, were not significant univariate or multivariate predictors of subsequent emergency visits.

The multivariate model, which included all prognostic variables as well as an emergency visit 30 days prior, demonstrated that a diagnosis of lymphoma, Hodgkin's disease, or myeloma (hazard ratio = 3.63), a diagnosis of melanoma (hazard ratio = 3.58), registration of six to 12 months (hazard ratio = .23), or registration of longer than 12 months (hazard ratio = .35) remained statistically significant (P<.05).

A similar pattern was found in subsequent emergency visits. In the multivariate model, a diagnosis of lymphoma, Hodgkin's disease, or myeloma, as well as patient registration of either six to 12 months or longer than 12 months, remained statistically significant factors for two emergency visits (P<.01) and for three or more emergency visits (P<.05). An additional prognostic variable specifically associated with an increased risk for two subsequent emergency visits, however, was found for patients 30 to 39 years of age (P<.05).

Discussion

The overall incidence rate of 10 visits per 100 patients per month (10/100/month) can be used as a baseline rate for capitation in a managed care environment. However, the data indicate that population and clinical demographics can affect capitation calculations. A younger patient population and one with newer patients could have an incidence rate two to three times baseline. In this study, patients 30 to 39 years of age had an incidence rate of 18/100/month, and the incidence rate for those registered less than one month was 29/100/month. While a new hospital or one with an aggressive marketing strategy would have higher emergency costs, one with an older population in terms of both age and chemotherapy experience would have lower costs. Likewise, cancer diagnosis can have a similar effect. Melanoma patients have a higher rate and breast cancer patients a lower rate. An institution serving breast cancer patients, particularly with adjuvant therapy, would have a lower incidence of emergency visits and lower costs.

The most plausible explanation for the high rate of emergency visits for patients with melanoma is the combination chemotherapy administered as part of our clinical investigations. Patients with melanoma are commonly referred to our center for aggressive treatment regimens. During the period of this study, the regimen consisted of 20 mg/m² of cisplatin plus 2 mg/m² of vinblastine daily for four days, and 800 mg/m² of dacarbazine on day 1. Some patients received this regimen plus a-interferon and interleukin-2.

Demographic and clinical prognostic factors can distinguish patients at greater risk of having an emergency visit while receiving outpatient treatment for cancer and may alert the health care team to populations needing interventions during chemotherapy to avoid subsequent emergencies. Patients registered less than seven months were at greatest risk of having an emergency visit and generated 95% of the emergency visits in this study. These patients are usually scheduled for more frequent clinic visits and more aggressive therapy. Newer patients are likely to be less informed about and less experienced in dealing with the side effects of chemotherapy. Pain, nausea, and weakness accounted for 45% of emergency visits in this study. Experienced patients may have adapted to symptoms that send less experienced patients to the emergency room. In addition, patients who had an emergency visit within 30 days prior to entrance to the study were four times more likely to have another emergency visit. Patient education, explicit instructions about signs or symptoms of true emergencies, and telephone follow-up may reduce the incidence of emergency visits for new patients.

Fever, which is often a symptom requiring an emergency visit, accounted for 27% of the emergency visits in our study. Although fever may not be preventable, treatment strategies such as outpatient antibiotics for febrile neutropenia can reduce the cost of the common downstream clinical event.

Future studies should further define the role of prognostic factors. For example, the low incidence rate of emergency visits by older patients may indicate that age is a surrogate for cancer diagnosis, extent of disease, or chemotherapy regimen. Type of therapy, whether adjuvant, curative, or palliative, also may be a predictive factor. Prospective studies that follow larger numbers of patients are needed to develop an accurate prognostic model. Additional variables such as comorbidity, extent of disease, and medications (including chemotherapy, antiemetics, and pain medications) may be more important factors than population demographics. Further studies are needed to determine if interventions such as patient education during chemotherapy or as part of emergency treatment can reduce the incidence of subsequent emergency visits. Also, analyses that focus on resource use and cost would provide useful data for care in capitated oncology markets.

References

1. Sandrik K Oncology: who's managing outpatient programs? Hospitals. 1990;64:32-37.
2. Goldberg J. Preface: Challenges of Ambulatory Medicine, Care and Research in Cancer in the 90's. Satellite Symposium, London, September 6, 1989.
3. 1992-1993 progress report. Conquest. 1994;8:20.
4. Patient care. Conquest. 1994;8:6.
5. Commission on Professional and Hospital Activities. The International Classification of Diseases, 9th revision, Clinical
   
6. Modification. Ann Arbor, Mich: Edwards Bros; 1980.
7. STATA Reference Manual: Version 3.0. Santa Monica, Calif: Computing Resource Center; 1992.
8. Bailar JC III, Mosteller F, eds. Medical Uses of Statistics. 2nd ed. Boston, Mass: NEJM Books; 1992.
   

Back to Cancer Control Journal Volume 3 Number 5