Income and survival in chronic dialysis patients.

The relationship between income and survival rates for chronic dialysis patients in Michigan was examined. To evaluate the relative risk (RR) of dying, by income, a Cox survival regression model was used to adjust for age, race (black versus white), gender, dialytic treatment modality, year of first end-stage renal disease (ESRD) therapy, and primary cause of ESRD. The average household income reported from census data for the ZIP Code of residence for each patient was analyzed as a socioeconomic indicator. Treatment modality on day 120 of ESRD was classified as either center hemodialysis (HD) or CAPD. All new patients, aged 20-59 and registered at the Michigan Kidney Registry between 1/1/80 and 12/31/87 were included in the study. Patients were followed from day 180 of ESRD until death, censoring at transplant, or 12/31/87. The adjusted relative risk of dying decreased for black patients by 3.3% per $1,000 increase in income (p less than 0.01), while the trend by income for white patients was negligible (p greater than 0.10). The difference in trends for the two groups was statistically significant (p less than 0.01). This is a surprising result, since white patients have higher death rates, overall, than do black patients, particularly among subgroups with diabetes and hypertension whose RR was 1.77 and 1.82, respectively. Poor socioeconomic status of the area of residence has a strongly negative effect on survival for black patients, but not for white patients. The reasons for the relationship of death rates with income, especially for black patients, need to be examined in greater detail.

Occupational and other exposures associated with male end-stage renal disease: a case/control study.

We conducted a case-control study of 325 men ages 30-69 who were diagnosed with end-stage renal disease (ESRD) between 1976 and 1984, and resided in four urban areas of Michigan in 1984. Cases were selected from the Michigan Kidney Registry and excluded men with diabetic, congenital, and obstructive nephropathies. Controls were selected by random-digit dialing and were pair-matched to cases for age, race, and area of residence. Telephone interviews were conducted with 69 percent of eligible cases and 79 percent of eligible controls. Risk of ESRD was significantly related to phenacetin or acetaminophen consumption (odds ratio(OR) = 2.66), moonshine consumption (OR = 2.43), a family history of renal disease (OR = 9.30); and regular occupational exposures to solvents (OR = 1.51) or silica (OR = 1.67). Particular occupational exposures with elevated risk were solvents used as cleaning agents and degreasers (OR = 2.50) silica exposure in foundries or brick factories (OR = 1.92), and silica exposure during sandblasting (OR = 3.83). Little or no trend of increased risk with duration of exposure was found for these occupational exposures, with the exception of silica in sandblasting. Limitations of these data include representativeness of cases, possible overreporting by cases, and misclassification of exposures inherent in self-reports.

Recovery from end-stage renal disease.

To evaluate the rate and associated factors for recovery of renal function in patients labeled by their nephrologists as having end-stage renal disease (ESRD), the data base of the Michigan Kidney Registry was used. All patients reported as starting treatment for ESRD between 1976 and 1985 (N = 7,404) were evaluated, excluding patients with acute tubular necrosis (ATN) or transplantation cases. While patients with ESRD due to diabetes and cystic diseases had lower recovery rates than average, patients with glomerulonephritis associated with a systemic illness, vasculopathies, and crescents had threefold to fourfold higher recovery rates. White race, older age, and later year of ESRD were associated with significantly higher recovery rates. Recovery rates did not differ substantially for patients receiving peritoneal dialysis or hemodialysis. Recovery occurred within 6 months of ESRD in approximately 48% of those recovering, 74% within 1 year, and lasted at least 1 year in 75% of the cases. The authors conclude that caution should be applied when the diagnosis of ESRD is made; the possibility of recovery should be sought and assessed, especially when early renal transplantation is considered.

Discontinuation of dialysis therapy as a cause of death.

Discontinuation of life-sustaining dialysis therapy led to death in 282 of 5,208 patients who started therapy for end-stage renal disease (ESRD) in Michigan during 1980-1985 with a follow-up through 1986. Based on life table estimates at 60 months after initiation of therapy, 9.4% of patients overall died due to termination of dialysis, 11% of females versus 8% of males (p = 0.02), 0.1-3.4% for ages less than or equal to 49 years versus 56% for greater than 80 years, 12% for white versus 4% for black patients (p less than 0.001) and 16% for diabetic ESRD patients (higher than any other group, p less than 0.05). The Cox regression model confirms these significant findings for race, diabetes and age, and reveals a significant 60% increase in overall withdrawals for the years 1980-1985 (1.10/year, p less than 0.02). A separate analysis of discontinuation of dialysis as the percentage of all 2,564 dialysis deaths in prevalence cases for 1980-1984 revealed an overall ratio of 8.9% with a significant difference for ages less than or equal to 64 versus greater than or equal to 65 (p less than 0.001), race (p less than 0.001) but not for prior transplant failure or continuous ambulatory peritoneal dialysis therapy. Whereas the results for age and diabetes were expected, the significant increase of dialysis withdrawal over time and the racial difference are unexplained by information available at the Michigan Kidney Registry and indicate the need for exploration by further studies.

Influence of race of cadaveric kidney donor and recipient on graft survival: a multifactorial analysis.

Actuarial survival analysis of 889 cadaver transplant patients between 1972 and 1981 in Michigan reveals functional graft (P = .0003) and patient (P = .004) survivals are improved when donors and recipients are of the same race (black or white). The Cox regression model for multifactorial analysis confirms the significantly lower graft survival for the mixed racial combination group with a relative risk of 1.27 (P less than .05). By this analysis, other significant factors adversely affecting the graft survival rates include diabetes as a cause of end-stage renal disease, earlier date of transplantation, shorter duration of prior dialysis, and a significant center effect. Patient survival has a significantly greater relative risk for the black to white racial combination, diabetes, earlier calendar year of transplantation, and age of patient. While the mixed racial group was slightly older (delta = 2 years), had more hypertension, less glomerulonephritis, and more HLA mismatches, our analysis by the Cox regression model suggests that these factors played only minor roles (P greater than .05) regarding graft survival rates. Therefore, our data suggest that independent of several other factors, cadaver kidneys have a better functional outcome when they are transplanted into recipients of the same race.

End-stage renal disease in Michigan. Incidence, underlying causes, prevalence, and modalities of treatment.

In Michigan from 1974 through 1981 the average annual end-stage renal disease (ESRD) incidence was 7.76 for males and 5.55 for females per 100,000 population. Those over 35 years of age had higher incidence rates. The average incidence for black ESRD patients was 20.75, compared with 4.78 for white ESRD patients. Thus, the risk of ESRD was 4.34 times higher in the black population. In 1981, the stated causes of ESRD in the ESRD population were diabetes mellitus (24.5%), hypertension (24.2%), and glomerulonephritis (20.9%). Black ESRD patients, compared to white, had relative risks of 3.8 for diabetes mellitus, 10.9 for hypertension, and 1.7 for glomerulonephritis. The ESRD point prevalence increased from 11.58 in 1974 to 31.68 in 1981. Males predominated over females; the sex-specific ESRD prevalence in 1981 being 36.74 and 26.83, respectively. Blacks predominated over whites; the black and white ESRD prevalences in 1981 were 80.27 and 24.81, respectively. Prevalence over these years increased faster for older age groups. Hemodialysis at a center has been the major ESRD treatment modality. The percentage of all ESRD patients on home hemodialysis steadily decreased from 1974 through 1981. Similarly, on a percentage basis, fewer patients were transplanted in 1981 than in 1974. The number of ESRD patients treated by chronic ambulatory peritoneal dialysis increased more than sevenfold from 1979 through 1981.

Case mix in end-stage renal disease. Differences between patients in hospital-based and free-standing treatment facilities.

This study examines the mix of cases in facilities for the treatment of end-stage renal disease in Michigan during the period January 1973 through September 1981. We compared 3135 patients treated in 29 hospital-based facilities with 307 patients treated in five proprietary, free-standing facilities. Patients were assigned to one of five severity groups on the basis of age, race, primary renal diagnosis, and accompanying conditions. The five severity groups were differentiated by the probability of death in the first year of treatment and the risk of death over the course of treatment. We then compared the distribution of patients in the five severity groups in hospital-based facilities with that in free-standing facilities. Hospital-based facilities had a higher percentage of patients in the higher-severity groups. When severity was measured by one-year survival, the difference was statistically significant. Sixty per cent of hospital-based patients were in the three highest severity groups, as compared with 50 per cent of patients in free-standing facilities. Within each severity group, hospital-based patients had a lower five-year survival rate than patients in free-standing facilities. Our findings suggest that the case mix in hospital-based facilities may include more severe cases than that in proprietary, free-standing facilities, but more data from more facilities will be needed before firm conclusions can be drawn. If the cost of providing services is related to case-mix severity, such data could have implications for federal reimbursement policies.

Analysis of survival of end-stage renal disease patients.

Traditional life-table analysis of differences in patient survival for various end-stage renal disease (ESRD) treatment modalities ignore the fact the ESRD patients face sequential risks because they frequently experience more than one mode of therapy. A modification of the usual life-table analysis is suggested as being more appropriate. This modified method takes into account the "time-to-treatment" bias, which, in this instance, is the time spent on the first modality of treatment (that is, center dialysis). The survival data of more than 2,000 ESRD patients in the State of Michigan during the 5-year period, 1974 to 1978, are used to illustrate this method.

Historical dates for neolithic sites of southeast europe.

Direct comparison of the radiocarbon contents of charcoal samples with those of bristlecone pine wood samples dated by tree rings shows that a full-fledged Neolithic with pottery and all the domesticated animals, except the horse, was present in southeast Europe as early as the 65th century B.C. The chronologies for the stratigraphic sequences of the settlements of Achilleion and Anza, based on a total of 37 La Jolla radiocarbon measurements, cover almost 1000 years.

Bristlecone Pine: Science and Esthetics: A 7100-year tree-ring chronology aids scientists; old trees draw visitors to California mountains.

A 7100-year tree-ring chronology has been developed for bristlecone pine, Pinus aristata Engelm., in the White Mountains of east-central California by the addition of data from long-dead specimens to the 4600-year record from living trees. These dendrochronological studies have major applications to climatic interpretations, radiocarbon analysis, and the dating of past events. The great age of these trees and the esthetic appeal of both the trees and their environment are drawing increasing numbers of visitors to the bristlecone pine areas. Concern is expressed for the preservation of this ancient wood.

Enclosed bark as a pollen trap.

Counts were made of pollen in traps formed by enclosed bark in two remnants of bristlecone pine, Pinus aristata Engelm., from the White Mountains of east-central California. The traps, dated by tree-rings at A.D. 350 and 1300 B.C., contained a major complex of pine-sagebrush pollen and traces of other species, representing the equivalent of the present vegetation.