Biomedical subjects

Philip F Rust

Publications and source records attributed to Philip F Rust.

5 recordsLinked to original sources

PubMed2004

Estimation of resting energy expenditure considering effects of race and diabetes status.

OBJECTIVE: To evaluate the impact of diabetes status and race, in addition to other covariables, on the estimation of resting energy expenditure (REE). RESEARCH DESIGN AND METHODS: Demographic, anthropometric, and clinical parameters were assessed in 166 adults of varying weights. Subjects were categorized by race (white versus black) and into three subgroups based on glucose tolerance (normoglycemia, impaired glucose tolerance, and type 2 diabetes), termed the diabetes status index (DSI). REE was measured by indirect calorimetry. A multiple regression model was established for optimal prediction of REE based on covariables. RESULTS: An average decrease in REE of 135 kcal/day independent of all other variables was observed in blacks (P < 0.001). DSI was found to be a significant covariable (P = 0.002) in predicting REE, which was observed to be higher in diabetic women. Therefore, race and DSI entered the multiple regression equation to predict REE as significant independent variables, together with lean body mass (LBM) and age x BMI interaction (P < 0.001). Overall, REE prediction resulted in an R(2) of 0.79 and a root mean square error of 136 kcal/day. These values indicate that the resultant equations could offer advantages over other key published prediction equations. The equations are: 1) REE(female) = 803.8 + 0.3505 x age x (BMI - 34.524) - 135.0 x race + 15.866 x LBM + 50.90 x DSI; and 2) REE(male) = 909.4 + 0.3505 x age x (BMI -34.524) -135.0 x race + 15.866 x LBM -9.10 x DSI. The predictive value of the equations did not diminish substantially when fat-free mass estimated by skinfold calipers was substituted for dual-energy X-ray absorptiometry scan measurements of LBM. CONCLUSIONS: Race and diabetes status are important when predicting REE, coupled with LBM, age, BMI, and sex. Race and DSI have not been considered in equations commonly used to predict REE. Their inclusion could improve individualization of dietary prescriptions for type 2 diabetic subjects and heterogeneous populations.

Alabama↗

PubMed2003

Analysis of clustered matched-pair data.

Evaluation of the performance of a new diagnostic procedure with respect to a standard procedure arises frequently in practice. The response of interest, often in a dichotomous form, is measured twice, once with each procedure. The two procedures are administered to either two matched individuals, or when practical, to the same individual. A large sample test for matched-pair data is the McNemar test. The main assumption of this test is independent paired responses; however, when more than one outcome from an individual is measured by each procedure, the data are clustered. Examples of such cases can be seen in dental and ophthalmology studies. Variance adjustment methods for the analysis of clustered matched-pair data have been proposed; however, because of unequal cluster sizes, variability of correlation structures within a cluster (within paired responses in a cluster as well as between paired responses in a cluster), and unequal success probabilities among the clusters, the performances of some available methods are not consistent. This research proposes a simple adjustment to the McNemar test for the analysis of clustered matched-pair data. Method of moments is used to calculate a consistent variance estimator. Using Monte Carlo simulation, the size and power of the proposed test are compared to those of two currently available methods. To illustrate practical application, clustered matched-pair data from two clinical studies are analysed.

Clinical Trials as Topic↗

PubMed2003

Analysis of clustered matched-pair data for a non-inferiority study design.

Hypothesis testing of matched-pair data has been adapted for equivalence (one- and two-sided) study designs; however, a statistical problem arises when more than one measurement is recorded for each study subject. Ignoring the correlation between the repeated measurements per subject may underestimate the standard error of the parameter estimate. A method of testing for non-inferiority or equivalence of clustered matched-pair data is not yet available. This paper proposes a Wald-type test statistic for a non-inferiority hypothesis and applies it to the comparison of two diagnostic procedures.

Computer Simulation↗

PubMed2002

Dose-volume relationship for acute side effects during high dose conformal radiotherapy for prostate cancer.

PURPOSE: To determine acute and late complications for bladder and rectum and to determine dose-volume correlations. METHODS AND MATERIALS: Sixty-four patients received definitive treatment for prostate cancer between January 1995 and December 1998 using conformal three-dimensional radiotherapy. Doses ranged from 72 to 80Gy. The acute and late side effects were gathered retrospectively, and graded according to Radiotherapy and Oncology Group criteria (RTOG). The patients were divided into two groups: or=76Gy (Group B) and had a mean follow-up of 32 and 22 months, respectively. RESULTS: No grades 3-4 acute, urinary or rectal toxicity was reported. Acute grade 2 rectal complications were seen in 10 and 18% of the patients in Groups A and B, respectively. They were observed at a mean dose of 38Gy. Acute grade 2 urinary symptoms were 33 and 47% for Groups A and B, respectively. They were seen at a mean dose of 43Gy. Acute rectal symptoms were dose-volume related. Patients without diarrhea had a mean rectal volume receiving a dose of 70Gy or more of 8.5 cm(3). However, patients with RTOG 2 diarrhea had a volume of 16.5 cm(3) (P=0.042). No dose-volume relationship for acute bladder symptoms or late complications were seen. Grades 1-2 late rectal and bladder complications were seen in 11 and 8% of the patients, respectively. None required hospital admission or transfusion. CONCLUSION: Radiotherapy to the prostate can be given at 80Gy. No grades 3-4 acute, urinary or rectal toxicity was reported. Acute rectal symptoms are dose-volume related.

Aged↗

PubMed2002

Criterion-related validity of a diarrhea questionnaire in HIV-infected patients.

Clinical trials evaluating HIV-related diarrhea have used varied unidimensional end points to assess diarrhea severity. We hypothesized that a self-reported measure of diarrhea that assesses stool form, stool frequency, and diarrhea morbidity would accurately portray the severity of HIV-related diarrhea. During a clinical trial for HIV-related diarrhea, we evaluated the instrument among 17 patients, comparing survey results with objective measures of diarrhea morbidity recorded concurrently. The survey scores demonstrated consistently high Spearman correlations with nursing assessment of stool form (0.6693), observed stool frequency (0.7023), and cumulative stool weight (0.8216), all recorded over six days of intensive inpatient observation (P < 0.01 for each). Of the three components of the survey, only the stool form assessment, which uses pictorial representations of stool consistency, correlated significantly across all three objective measures (0.8069-0.8792). In demonstrating the concurrent, criterion-related validity of this survey, we found it helpful for evaluating HIV-related diarrhea and suggest its utility for HIV-seronegative subjects as well.

Adult↗