William H. Barker

Influenza vaccination programs for elderly persons: cost-effectiveness in a health maintenance organization.

Annual influenza vaccination of elderly and chronically ill persons has been a long-standing recommendation of the U.S. Public Health Service [1, 2]. Recent studies have documented the health benefits of annual influenza vaccination [3-10], but despite the exhortations of the Surgeon General and the clear evidence of vaccine efficacy, many persons in high-risk groups fail to receive the recommended vaccinations [11, 12]. Because of the low level of compliance with the U.S. Public Health Service influenza vaccination guidelines [13], the Centers for Disease Control and Prevention (CDC) have proposed new strategies to increase the proportion of high-risk persons who are immunized [14]. One such strategy is to promote assessments of the net financial costs to health maintenance organizations of operational vaccine delivery programs. Successful demonstrations of net financial benefit should encourage managers of organized medical care programs and health insurance companies to advocate improved vaccine delivery. Methods General Methods Setting The study was done at Kaiser Permanente, Northwest Region, a prepaid group practice health maintenance organization (HMO) that includes 20% of the Portland, Oregon-Vancouver, Washington, Standard Metropolitan Statistic Area population. Members receive almost all of their medical care from the health plan, and each contact they make with the HMO is recorded in a single, centralized chart. Epidemic Periods Epidemic periods were defined as periods during which influenza viruses circulated persistently in Oregon according to influenza virus isolation dates reported by the Oregon State Virology Laboratory. The eight epidemic periods defined using this approach are shown in Table 1. The study period for the nonepidemic 1981-1982 reference period was defined by averaging the months and days of the epidemic periods. The number of specimens tested ranged from 118 in 1981-1982 to 652 in 1988-1989. Table 1. Influenza Epidemic Periods and Study Samples Influenza viruses were isolated from only 9 of 118 specimens (8%) tested in the 1981-1982 nonepidemic reference period; B viruses were isolated from two specimens obtained in late April. During the epidemic study periods, influenza viruses were typically isolated from 25% of specimens, isolations were sustained, and isolation frequency distributions described epidemic curves. Participants Participants included in a study period were Kaiser Permanente members 65 years of age or older, each with at least 1 month of eligibility during that period and during the September-December vaccination period. These members represent almost all elderly persons enrolled in the HMO. High-risk participants were defined as those who had had medical care contacts for chronic pulmonary (ICDA [International Classification of Diseases, Adapted] codes 9:491-493.9, 496, 500-505, 506.4, 508.1, 510-516, 714.8), cardiovascular (112.81, 130.3, 393-398, 401.0, 402-405, 410-414, 416, 420-429, 430-438, 440.1, 785.2-.3), metabolic (250-250.9, 571-571.9), renal (274.10, 580-583.9, 585, 587-588.0), or malignant (140-208.9) conditions. These risk factors for influenza-related complications are defined by the CDCs Advisory Committee for Immunization Practices. Data Sources An automated inpatient database was used to identify all hospitalizations for pneumonia and influenza during the nine study periods. This database contains discharge diagnoses and records of inpatient procedures and is the source of the discharge summaries. The outpatient database contains outpatient diagnoses and records of procedures for a continuously updated research sample composed of 5% of elderly health plan members. Each month, a random 5% sample of all new elderly Kaiser Permanente subscriber units is added to the cumulative pool of enrollees whose records are abstracted. Automated outpatient diagnoses were available through 1987. Medical record abstractions were the source of outpatient diagnoses for the first quarter of 1988. Inpatient high-risk discharge diagnoses made during the 3 years before the study period were obtained from the inpatient database. Outpatient high-risk diagnoses made during the year before the study period were obtained from the outpatient database and by chart abstraction. Influenza and pneumococcal vaccination status was abstracted from the medical records for pneumonia and influenza cases that were not in the 5% research sample. Automated vaccination data through 1987 were available for cases and controls in the research sample. Medical record abstractions were the source of 1988-1989 vaccination data for all study participants. Participants receiving influenza vaccine after the start of epidemics were classified as unvaccinated. Case-Control Assessment of Vaccine Effectiveness Population-based, casecontrol designs were used to estimate influenza vaccine effectiveness in preventing medically attended episodes of pneumonia and influenza. To exclude pneumonias that were unlikely to be influenza related, we included only persons with pneumonia and influenza who were admitted to medical services. Because we based participant selection on discharge diagnoses, participants with both hospital- and community-acquired pneumonia and influenza were included. Pneumonia and Influenza Cases and Controls Participants who were hospitalized with pneumonia and influenza during the study period, who were eligible Kaiser Permanente members, and who had a pneumonia and influenza ICDA-9 code (480-483,485,486,487) listed as a discharge diagnosis were included as cases of hospitalized pneumonia and influenza. Controls were members of the 5% research sample who met the study eligibility criteria and who were not hospitalized with pneumonia or influenza during the given period. Pneumonia and influenza deaths during a study period were defined as hospitalized patients with pneumonia and influenza who died in the hospital. Controls were members of the 5% research sample who were not pneumonia and influenza hospital deaths during that period. Outpatient pneumonia and influenza cases included members of the 5% research sample who had an outpatient episode of pneumonia and influenza with no inpatient component during the given study period. Controls were members of the 5% research sample who did not have an outpatient episode of pneumonia and influenza during the given period. Cases and controls were group matched for high-risk status. Logistic regressions were used to adjust influenza vaccine effects on occurrence of pneumonia and influenza episodes for differences in age, sex, months of HMO eligibility, and pneumococcal vaccine status. Vaccine Effectiveness Relative risks for pneumonia and influenza episodes in unvaccinated and vaccinated populations were estimated by the adjusted exposure (unvaccinated) odds ratios. The effectiveness of influenza vaccine in preventing pneumonia and influenza episodes was computed from the estimated relative risk as effectiveness =1-(1/relative risk). Pneumonia and Influenza Episodes Prevented The population-based, casecontrol design allowed unbiased estimation of the total number of participants vaccinated and of the pneumonia and influenza episode rates among unvaccinated participants. The product of these estimates multiplied by the vaccine effectiveness is the estimated number of pneumonia and influenza episodes prevented by influenza vaccination: pneumonia and influenza episodes prevented = (number of participants vaccinated)(effectiveness of vaccination)(pneumonia and influenza episode rate among unvaccinated participants). Statistical Methods The units of analysis for period-specific vaccine effectiveness analyses were persons. A case for a given period had an episode of pneumonia or influenza during that period. A control for a given period did not have an episode of pneumonia or influenza during that period. The same person could appear as a case in more than one period. Person-periods were the units of analysis for aggregate analyses. A person contributed a person-period of observation to each period when study criteria were met. Some members of the 5% research sample were controls in some periods and cases in other periods. Study participants not in the 5% research sample could only contribute person-periods as hospitalized cases. Risks for pneumonia and influenza episodes during high-risk and nonhigh-risk person-periods are separately modeled as logistic functions of influenza vaccine status, pneumococcal vaccine status, age, sex, and length of observation time. The SAS logistic procedure was used to estimate odds ratios and confidence intervals for model variables. The Hosmer-Lemeshow statistic was used to assess the goodness of fit of logistic models. Cost Analysis Methods Medical Care Costs of Pneumonia and Influenza Episodes Costs of providing inpatient care for pneumonia and influenza episodes were obtained from Kaiser Permanente accounting systems for the various patient care cost centers. Costs of providing outpatient care were estimated from the 5% research sample, using relative value units included in the outpatient database and unit costs for accounting cost centers. Cost of Vaccine Delivery Costs of the vaccine delivery program were estimated by a micro-costing approach and included overhead costs. The purchase cost of vaccine was obtained from administrative records and included all vaccines used and wastage. Distribution costs were allocated based on the proportion of direct drug costs represented by influenza vaccine. Two methods of promoting the vaccination program were identified: an article in the member newsletter and referrals by nurses, generally by the telephone advice nurse. Time estimates were obtained from interviews with providers, and labor costs per hour were obtained from Kaiser Permanente administrative records. Cost-Effectiveness Ratios Three cost-effectiveness measures were computed: cost per prevented episode of outpa

Excess pneumonia and influenza associated hospitalization during influenza epidemics in the United States, 1970-78.

In this study, excess rates of pneumonia and influenza (P&I) associated hospitalization during influenza A epidemics which occurred in the United States between 1970-78 were computed utilizing unpublished data from the National Hospital Discharge Survey (NHDS). Excesses occurred at rates of 35, 93, and 370 per 100,000 persons per epidemic for age groups 15-44, 45-64, and 65+ years. There was no evidence of a persisting excess or a compensatory decline in P&I hospitalization during post-epidemic months. An average excess of about 172,000 hospitalizations per epidemic at a cost in excess of

Pneumonia and Influenza Deaths During Epidemics: Implications for Prevention

300 million was computed. The study quantifies a major impact of epidemic influenza upon health and health services, much of which may be preventable, and illustrates an important use of unpublished data contained in the NHDS.

Changing Incidence and Survival for Heart Failure in a Well-Defined Older Population, 1970–1974 and 1990–1994

Pneumonia and influenza (P&I) deaths among adults during epidemics of influenza A (H3N2) virus are reviewed and risks of such deaths according to age and presence of chronic disease are estimated from medical records of a large group practice. Thirty-eight deaths occurred among 310 persons hospitalized with P&I. Flu-like symptoms occurred in 30 patients (79%), 26 patients (68%) were older than 65 years, 36 patients (95%) had chronic disease, and approximately half were medically stable before the terminal episode. These values were similar to those of P&I deaths during nonepidemic periods. Pneumonia and influenza death rates ranged from fewer than ten to more than 600 per 100,000 among healthy vs chronically ill adults. Highest rates (870 per 100,000) occurred in persons with both cardiovascular and pulmonary disease. Application of these findings to influenza vaccination strategies in clinical practice is discussed.

Impact of type A influenza on children: a retrospective study.

Background— An epidemic increase in heart failure (HF) mortality, hospitalization, and prevalence rates has been observed among older persons in recent years. It is unclear whether this reflects an increase in incidence or survival. Methods and Results— We conducted a retrospective cohort study comparing HF in 1970 to 1974 and 1990 to 1994 among persons ≥65 years old belonging to a large, well-defined population with complete medical records available for research. Using Framingham clinical criteria, we identified incident cases of HF in the respective periods. Age-specific and age-adjusted incidence, mortality, and survival rates were compared. Cox proportional-hazards models were used to assess association of comorbidities and medications with survival. During 38 800 and 127 419 person-years for 1970 to 1974 and 1990 to 1994, respectively, 387 and 1555 confirmed incident cases were identified. When adjusted for age, incidence increased by 14% (95% CI 2% to 28%). Increased incidence tended to be greater for older persons and for men. Based on 5-year follow-up and adjustment for age and comorbidities, the mortality hazards decreased 33% (95% CI 14% to 48%) among men and 24% (95% CI −1% to 43%) among women. Conclusions— The epidemic increase in HF among the older population between the 1970s and 1990s is associated with increased incidence and improved survival, with both of these effects being greater in men.

INTERNATIONAL OUTBREAK OF SALMONELLA EASTBOURNE INFECTION TRACED TO CONTAMINATED CHOCOLATE

Excess morbidity was studied during influenza A epidemics (1968-69, 1972-73) among children in a large prepaid group practice program. Excess rates of hospitalization for influenza-related conditions, primarily pneumonia and bronchitis, ranged from 5 per 10,000 (95 per cent confidence limits (CL): 1 to 9) for non-high-risk children to 29 per 10,000 (95 per cent CL: 5 to 53) for children with high-risk conditions. The relative increases in hospitalization rates were greatest for 5-14 year old boys: 278 per cent and 104 per cent increases for high-risk and non-high-risk boys, respectively. The absolute increase was greatest for 0-4 year olds. The excess rate of ambulatory medical care contacts, 2.6 per 100 (95 per cent CL: -1.6 to 6.8 per 100) was not statistically significant. Excess hospitalization rates among 0-14 year olds during epidemics were three to five times larger than those for persons between 15 and 64 years of age but only one-fifth the rate of persons over age 65.

Acute Respiratory Tract Infection in Daycare Centers for Older Persons

Between Dec. 4, 1973, and Feb. 15, 1974, 80 cases of infection due to Salmonella eastbourne, previously a rare isolated serotype in the United States, were reported from twenty-three States. An additional 39 cases were reported from seven Provinces in Canada during a similar period. A telephone case-control study implicated Christmas-wrapped chocolate balls manufactured by a Canadian company as the vehicle of transmission. S. eastbourne was subsequently isolated from several samples of leftover chocolate balls obtained from homes where cases occurred. Investigation of the factory revealed that the contaminated Christmas and Easter chocolates, and a few chocolate items for year-round sale, had been produced between May and October, 1973. Bacteriological testing of samples taken at the plant implicated cocoa beans as the probable source of the salmonella organisms which, in the low-moisture chocolate, were able to survive heating during production. This outbreak and the finding of salmonella of other serotypes in chocolates produced by another manufacturer suggest that chocolate-related salmonellosis may be a significant public-health problem.

Rates, patterns, causes, and costs of hospitalization of nursing home residents: a population-based study.

OBJECTIVE: To evaluate the rate of specific pathogens and clinical syndromes associated with acute respiratory tract infections (ARTI) in frail older persons attending daycare.

Geriatric Consultation Teams in Acute Hospitals: Impact on Back‐up of Elderly Patients

OBJECTIVES Hospitalization of nursing home residents is a growing, poorly defined problem. The purposes of this study were to define rates, patterns, costs, and outcomes of hospitalizations from nursing homes and to consider implications for reducing this problem as part of health care reform. METHODS Communitywide nursing home utilization review and hospital discharge data were used to define retrospectively a cohort of 2120 patients newly admitted to nursing homes; these patients were followed for 2 years to identify all hospitalizations. Resident characteristics were analyzed for predictors of hospitalization. Charges and outcomes were compared with hospitalization of community-dwelling elders. RESULTS Hospitalization rates were strikingly higher for intermediate vs skilled levels of care (566 and 346 per 1000 resident years, respectively). Approximately 40% of all hospitalizations occurred within 3 months of admission. No strong predictors were identified. Length of stay, charges, and mortality rates were higher than for hospitalizations from the community. CONCLUSIONS Hospitalizations from nursing homes are not easily predicted but may in large part be prevented through health care reforms that integrate acute and longterm care.

Trends in Hypertension Prevalence, Treatment, and Control In a Well-Defined Older Population

Back‐up of elderly patients in hospital awaiting long‐term placement has become a major problem in some areas of the United States and elsewhere. In 1982, geriatric consultation teams (physician, nurse, and social worker) were introduced into six acute hospitals in Monroe County, New York, to help alleviate the problem through more attention to restoration of patient function and comprehensive discharge planning. Over a six‐month period, 4,328 newly hospitalized patients aged 70 or older were screened, and geriatric consultations were provided for 366 (8.5 per cent) who were judged to be at risk of requiring prolonged hospital stays. During this period, the mean monthly census of elderly patients backed up in hospital declined 21 per cent, a reversal of previous rises that could not be explained by any other identifiable factors. The impact was on length of stay on back‐up status rather than rate of entry to that status. A variety of medical, rehabilitative, and social interventions accounted for this outcome. A number of health care system barriers to expeditious rehabilitation and discharge of hospitalized elderly patients were identified. Geriatric consultation was deemed useful for implementation in acute hospitals in other settings.