Biomedical subjects

S Hunsberger

Publications and source records attributed to S Hunsberger.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Testing for differences in changes in the presence of censoring: parametric and non-parametric methods.

Some commonly used parametric and non-parametric methods for analysing repeated measures with incomplete observations are briefly reviewed. The performances of these methods in the presence of completely random, as well as informative censoring are compared in simulated experiments generated under the linear random effects model with parameter values derived from realistic examples. The effects of some moderate model deviations are also compared. The results indicate that in the presence of informative censoring, the usual parametric and nonparametric methods derived under the assumption of random censoring could either suffer severe loss of power or provide false positive results. The conditional linear model for informative censoring when used in conjunction with the bootstrap variance estimation procedure performed well under both random and informative censoring mechanisms. The non-parametric procedure obtained by ranking the individual summary statistics, although not as efficient as the conditional linear model with robust variance, also performed relatively well in most situations. Therefore, in situations in which informative censoring is likely to occur it is important to select the proper method of analysis to test for the informativeness of censoring and to account for its effects.

Bias↗

PubMedDate not supplied

Stochastic curtailing and conditional power in matched case-control studies.

New methodology for early stopping of observational epidemiologic studies is developed. To indicate the likelihood of a positive result at the end of a study, the conditional power (CP) is calculated using an approach similar to that of Halperin et al. Given the current result, the conditional probability of a positive result for the entire study is determined. An expression relating the new approach to an approach given by Lan and Wittes is derived. As an example, the CP is calculated based on information from the first third of a matched case-control study embedded in an epidemiological study.

Antibodies, Viral↗

PubMedDate not supplied

Prediction equations for handgrip strength in healthy Indian male and female subjects encompassing a wide age range.

PRIMARY OBJECTIVE: Handgrip strength is a simple index of skeletal muscle function and a functional index of nutritional status. A major lacuna in the use of handgrip strength is the limited availability of normative data. The main objective of this paper was to develop prediction equations for handgrip strength in Indians covering a wide age range. METHODS: Handgrip strength and basic anthropometric parameters were measured in 1024 healthy Indian subjects of both genders (613 males, 411 females) between the ages of 5 and 67 years. The sample was randomly divided into two sets; one set (n = 677) was used to develop the prediction equations for handgrip strength and the other (n = 347) was used to validate the equations. Each data set was further divided into two subsets (adults > 18 years, sub-adults <or= 18 years), since separate equations were developed for adults and sub-adults. Simple models that included one of the following variables: height, forearm circumference and age as well as a full model that included all three variables were developed. Gender was included in all models. RESULTS: In general, all simple models predicted handgrip strength better in sub-adults (R(2) = 0.78-0.81) as compared to adults (R(2) = 0.52-0.57). The best simple model in sub-adults was that which included age and gender (R(2) = 0.81), while for adults it was that which included forearm circumference and gender (R(2) = 0.57). The full model explained a further 3.4-6.5% of the variance in handgrip strength in sub-adults and a further 6.3-13.3% in adults. CONCLUSIONS: The simple and full model equations for handgrip strength had high predictive power in the sub-adults, while they were less predictive in adults. The equations will be of particular use in physiological studies assessing muscle strength and in clinical investigations of patients with malnutrition and neuromuscular disorders.

Adolescent↗

PubMedDate not supplied

Treatment of acute myocardial infarction: does the type of hospital make a difference? PPAMI Study Group.

There is sparse data on the treatment practices being followed for acute myocardial infarction at various hospitals that differ in their financial infrastructure, availability of facilities and attachment to a medical college. In this prospective observational study, we evaluated the treatment practices for acute myocardial infarction, its appropriateness based on ACC/AHA guidelines and possible influence by type of hospital and certain patient characteristics. Thrombolysis, beta-blockers and angiotensin-converting enzyme-I inhibitors were used in 674 (63%), 506 (47%) and 413 (38%) respectively of 1072 patients. However, when evaluated according to ACC/AHA guidelines, appropriate use was noted in 83 percent, 78 percent and 99.3 percent, respectively. Thrombolysis was inappropriately denied to 14.7 percent patients whereas in 2.4 percent it was used contrary to recommendations. The most common reason for ineligibility for thrombolysis was late arrival. Beta-blockers were denied to 25.1 percent patients. Decision on use of angiotensin-converting enzyme-I was appropriate in most patients. Aspirin was used in 1027 (95.8%) patients. Government hospitals were least likely to thrombolyse a patient as compared to private, industrial and voluntary hospitals; however, this difference was not seen with the use of beta-blockers and angiotensin-converting enzyme-I. Hospitals attached to medical colleges follow guidelines for use of thrombolysis and beta-blockers more closely than non-teaching hospitals. To conclude, evaluation of appropriateness of a therapeutic modality is of greater clinical significance than mere absolute use. Benefits of thrombolytic therapy can be extended by minimising pre-hospital delay; and there is scope for improved utility of beta-blockers which are cost-effective. In addition, the hospital type also has an impact on the treatment practice being followed for acute myocardial infarction.

Adrenergic beta-Antagonists↗