Epidemiologic trends in the hospitalization of elderly Medicare patients for pneumonia, 1991-1998.

OBJECTIVES: This study determined hospitalization rates of elderly Americans for pneumonia from 1991 through 1998. METHODS: Epidemiologic data were described for 273,143 pneumonia hospitalizations. RESULTS: Annual hospitalizations for aspiration pneumonia increased by 93.5%. Pneumonia hospitalization rates increased steeply with age, especially among men. Black men were at highest risk for aspiration, unspecified, Klebsiella, "other gram-negative," and staphylococcal pneumonia; White men had the highest Haemophilus and pneumococcal pneumonia rates. Among women, Blacks predominated in aspiration and Klebsiella pneumonia; Whites had the highest Haemophilus and bronchopneumonia rates. CONCLUSIONS: An epidemic of hospitalization for aspiration pneumonia smoldered over 8 years. Significant disparities existed in hospitalization risks by race, sex, and principal diagnosis.

The epidemiology of hospitalization of elderly Americans for septicemia or bacteremia in 1991-1998. Application of Medicare claims data.

PURPOSE: To describe the epidemiology of hospitalization of elderly Americans for septicemia or bacteremia. METHODS: Medicare claims data for discharges from 1991 through 1998 were used to study 75,920 hospitalizations with the principal diagnosis of septicemia or bacteremia in patients aged 65 years or older. RESULTS: "Unspecified septicemia" was the commonest principal diagnosis, followed by septicemia due to Escherichia coli or staphylococci. From 1991 through 1997, annual discharges for "unspecified septicemia" increased 108%, and those for pneumococcal septicemia increased 310%. Decreases in reported septicemia were seen after increases in the proportion of beneficiaries in Medicare health maintenance organizations. Discharge rates for septicemia principal diagnoses increased steeply with age. Age-specific discharge rates were usually highest for black men and lowest for white women. Exceptions included septicemia due to E. coli, with white men at low risk, and pneumococcal septicemia, without significant differences between races or sexes. The case-fatality rate in hospital ranged from 4.2% with "bacteremia" and 6.9% with E. coli septicemia to 22.2% with "septicemia due to gram-negative organism, unspecified," and 26.8% with "unspecified septicemia." Staphylococcal septicemia, septicemia due to pseudomonas, and septicemia due to anaerobes were the costliest common principal diagnoses in terms of the mean duration of hospital stay. CONCLUSIONS: Unexplained sharp increases were reported in hospitalization for septicemia or bacteremia in elderly Americans. Marked variation by race and sex were evident in discharge rates with these principal diagnoses. Prognosis and average cost of treatment also differed substantially among common rubrics. Further investigation of individual diagnoses should concentrate on explaining secular trends, exploring the basis for variation by race and sex, and elucidating risk factors for poor clinical outcomes.

Epidemiologic trends in the evaluation and treatment of lower urinary tract symptoms in elderly male Medicare patients from 1991 to 1995.

PURPOSE: We describe utilization of procedures to reveal recent epidemiologic trends in evaluation and management of benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Medicare claims data reflect clinical practice in the vast majority of elderly Americans. The standard 5% beneficiary sample from Medicare claims files for 1991 to 1995 was searched to identify men 65 years old or older with invoices containing diagnostic and procedure codes indicative of prostate disease or lower urinary tract symptoms. Physician/supplier file claims for this sample of patients were used to identify diagnostic and therapeutic procedures relevant to BPH. RESULTS: During these 5 years claims for uroflowmetry peaked in 1993, filling cystometry gradually declined and pressure flow studies increased. Transurethral resection of the prostate decreased 43%, with even steeper reductions for open prostatectomy. The proportion of transurethral resections performed in hospital inpatients ebbed from 96 to 88%. Age specific operative rates for transurethral resection were highest in the ninth decade, and during the 5 years operative rates generally declined more among white than black men of the same age. Although urethrocystoscopy and excretory urography explicitly for BPH decreased markedly, from 1992 to 1995 the proportion of transurethral resections preceded by urethrocystoscopy for any indication increased from 45 to 47%, while excretory urograms were still obtained before 36% of these operations in 1992 and decreased to 26% in 1995. CONCLUSIONS: Evaluation and treatment of lower urinary tract symptoms in elderly men in the United States changed rapidly between 1991 and 1995, with a sharp decline in invasive therapy for BPH.

Assessment of prognostic factors and projection of outcomes in renal transplantation.

Analysis of data on renal transplantation collected in two large multicenter observational studies resulted in the concordant identification of five factors that correlated highly and at a substantial level of statistical significance with the outcome of unrelated cadaveric donor transplantation (i.e., they were associated with differences in one-year graft survivals of 0.07-0.21 and P values less than 0.05). These factors were: blood transfusions prior to the transplant, race of the recipient (white or black), prior failure in transplantation, level of sensitization to lymphocyte alloantigens, and diabetes as the cause of end-stage renal failure. Multivariate analysis with a mathematical survival model confirmed the importance and independence of these prognostic factors. Matching of HLA antigens appeared to be beneficial in both studies, but failed to attain high statistical significance in one. Systematic differences in the use of pretransplant splenectomy and, probably, in the nature of the antilymphocyte serum or globulin led to discordance in assessment of the importance of these factors in the two studies. Although advanced age (greater than 45 years) of the recipient was associated with reduced graft survival in both studies, analysis by means of the model failed to detect a significant correlation between the recipient's age and the outcome in one of the studies because the relation was not monotonic. In an illustration of their utility in the detailed assessment of performance, the prognostic factors were found to substantially account for the markedly superior results at one center and partly for lower graft survivals at another. These prognostic factors may be used to predict probable outcomes for populations and for individual patients subjected to particular arrays of conditioning strategies.

Dose-responses of guinea pigs to diazepam at recompression depths.

Dose-responses to diazepam were studied in guinea pigs at the recompression pressures used for the treatment of gas embolism and decompression sickness. The conditions and the doses were randomly assigned. Sufficient exposure to 6 ATA air, 3 ATA oxygen, or 1 ATA air was allowed in the hyperbaric chamber before diazepam was administered intravenously. Loss of righting reflex and its return were the end points for sleep and awakening, respectively. The data were analyzed with a mathematical model for dose-response and duration of effect. Results were: (1) in 1 ATA air, widely varying doses induced sleep of long duration; (2) in 6 ATA air, sleep was induced with small doses; and (3) in 3 ATA oxygen, sleep was induced with large doses. The duration of sleep under hyperbaric conditions was shorter than at sea level pressure. The null hypothesis, which assumed similar dose-responses and durations of sleep under these three conditions, was rejected. The dose and duration of diazepam's effect during recompression apparently depend on the pressure and the gas composition used.

A proposal for the analysis of kidney graft survival.

A survival analysis using a model provides numerous advantages over other approaches. The effectiveness of concomitant variables in describing the data can be evaluated whether the variables are continuous or dichotomized. We can evaluate the effectiveness of such variables in describing either short- or long-term components of the risk. The expected life span of the graft may be computed with the model and complements the insight obtained from the more commonly displayed survival curves.