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Biomedical subjects

B V Shah

Publications and source records attributed to B V Shah.

18 recordsLinked to original sources
PubMed1996

Innovative strategies using SUDAAN for analysis of health surveys with complex samples.

Large-scale health surveys provide a wealth of information for addressing problems in health sciences research. Designed for multiple purposes, these surveys frequently have large sample sizes and extensive measurements of demographic and socioeconomic characteristics, risk factors, disease outcomes and health care service use and costs. Complex features of the sampling design typically employed to select the survey sample, coupled with the vast amount of information available from the survey database, underlie issues that must be addressed during data processing and analysis. Numerous articles in the literature have focused on the debate of whether or not, and how, to control for features of the sample design during data analysis. Traditional statistical methods for simple random samples and the software that accompanies them have historically not had the capacity to account for the survey design. Recent advancements in statistical methodology for survey data analysis have greatly expanded the analytical tools available to the survey analyst. Commercial software packages that incorporate these methods offer the analyst convenient ways for applying such tools to large survey databases in an easy and efficient manner. We present an overview of analysis strategies for survey data and illustrate their application via the SUDAAN software system. Examples for analyses are provided through data from two large US health surveys, the National Health Interview Survey and the Longitudinal Study of Aging. Questions of both a cross-sectional and longitudinal nature are addressed. The examples involve logistic regression, time-to-event analysis, and repeated measures analysis.

Aged↗
PubMed1996

Renal involvement in multiple myeloma.

The present study is a retrospective chart analysis of 33 patients who satisfied the diagnostic criteria of multiple myeloma. Sixteen (49.5%) of these 33 patients developed renal failure at some point in time. The mean age +/- 1SD of patients who developed renal failure was 59.2 +/- 13 years (range 34-85 years). There were 12 males and 4 females. The precipitating factors for renal failure were dehydration (12.5%), hypercalcemia (62.5%) and use of non-steroidal antiinflammatory drugs (6.2%). Hypercalcemia was observed in 10 of the 16 patients who developed renal failure while it was seen in only 4 of the 17 cases who did not develop renal failure (relative risk 5.4). In 11 (68.7%) patients, the renal function improved with hydration, treatment of hypercalcemia and chemotherapy. The 1 and 3 year actuarial survival of patients with renal failure and multiple myeloma was 87% and 74% respectively.

Adult↗
PubMed1992

Spontaneous changes in the rate of decline in reciprocal serum creatinine: errors in predicting the progression of renal disease from extrapolation of the slope.

The slope of reciprocal serum creatinine (1/Pcr) versus time has been used to measure the rate of progression of chronic renal disease, predict the interval until onset of end-stage renal disease, and assess the effect of therapy. In order to determine the errors that might result from extrapolating the slope of 1/Pcr versus time beyond the interval of observation, we applied a method of linear regression analysis to search for spontaneous changes in slope in 21 patients from New England Medical Center and 56 patients in three published studies in whom the decline in 1/Pcr appeared constant (r greater than or equal to 0.84 for the correlation of 1/Pcr versus time). Significant changes in the slope (breakpoints) were identified in one third to one half of the 77 patients and appeared to be spontaneous. The second slope was less steep in 49 patients (6.1%); the mean value for serum creatinine at the time of the breakpoint was 5.3 mg/dL; the mean change in slope (absolute value) was 0.005 dL/mg/month (adults) and 0.017 dL/mg/month (children); and the mean error in prediction of the interval until the final value for serum creatinine was 27% of the actual interval. We conclude that spontaneous breakpoints in the slope of 1/Pcr versus time are very frequent, even among patients with an apparent constant rate of decline. Breakpoints may cause errors in extrapolating the slope to predict the interval until the onset of end-stage renal disease and to assess the effect of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

Nosocomial infections in U.S. hospitals, 1975-1976: estimated frequency by selected characteristics of patients.

To obtain estimates of the frequency of nosocomial infections nationwide, those occurring at the four major sites--urinary tract, surgical wound, lower respiratory tract and bloodstream--were diagnosed in a stratified random sample of 169,526 adult, general medical and surgical patients selected from 338 hospitals representative of the "mainstream" of U.S. hospitals. We estimate that in the mid-1970s one or more infections developed in 5.23 percent (+/- 0.16) of the patients and that 6.62 (+/- 0.24) infections occurred among every 100 admissions. Risks were significantly related to age, sex, service, duration of total and of preoperative hospitalization, presence of previous nosocomial or community-acquired infection, types of underlying illnesses and operations, duration of surgery, and treatment with urinary catheters, continuous ventilatory support or immunosuppressive medications. Seventy-one percent of the nosocomial infections occurred in the 42 percent of patients undergoing surgery and 56 percent in the 38 percent financed by Medicare, Medicaid or other public health care plans.

Adolescent↗
PubMedDate not supplied

Brown tumor of the hard palate in secondary hyperparathyroidism.

Jaw bones are rarely involved in secondary hyperparathyroidism. We report a case of 13 year old girl who presented with progressive chronic renal failure and secondary hyperparathyroidism. Five months after beginning of hemodialysis, a large brown tumor developed on the hard palate, extending to the maxilla causing difficulty in swallowing and breathing. She died of massive intestinal hemorrhage five months after excision of the mass.

Adolescent↗