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Biomedical subjects

T Lumley

Publications and source records attributed to T Lumley.

13 recordsLinked to original sources
PubMed2000

A comparison of standard gamble, time trade-off, and adjusted time trade-off scores.

OBJECTIVE: To adjust patients' time trade-off (TTO) scores using information on their utility functions for survival time to derive a measure of health state utility equivalent to the standard gamble (SG). METHODS: A sample of 199 cardiovascular patients were asked three TTO and SG questions (to assess their own health state), and three certainty equivalent questions (to assess their utility function for survival time) in an interview. RESULTS: Patient's utility functions for time were increasingly concave, but being unable to model this successfully, a constant function with an averaged level of concavity was used. The raw TTO scores were significantly higher than SG scores, while the adjusted TTO scores were equivalent to the SG. CONCLUSIONS: Raw time trade-off scores will give biased estimates of health state utility when patients' utility functions for time are not linear, but these can be adjusted to yield true utilities. The constant proportional risk-posture assumption of the conventional QALY model, on which previous attempts to adjust time trade-offs have been based, was not supported by the data.

Cardiovascular Diseases↗
PubMed2000

Variation in the quality of lumbar spine MR images in Washington State.

PURPOSE: To investigate the variation in quality of lumbar spine magnetic resonance (MR) images as a function of type of ownership of the imaging center, number of studies performed per month, specialty training of the image interpreter, and field strength of the MR unit. MATERIALS AND METHODS: Data were collected from all imaging facilities in western Washington state that received reimbursement from the Washington State Health Care Authority. Three readers with expertise in spine imaging, who were blinded to center and patient identification information, rated the technical image quality of each study. All MR images of the lumbar spine (maximum of six) paid for by the health care authority were evaluated. If a center had performed more than six studies, then six were randomly selected for evaluation. RESULTS: Variation in quality scores among sites was significant (P =.001). Field strength was the strongest predictor of better quality. Poorer quality was associated with for-profit ownership, a larger number of radiologists at the site reading MR images, and a larger percentage of studies checked by a radiologist prior to the end of the examination. CONCLUSION: There was significant variation in the quality of MR images of the lumbar spine, and at least a portion of this variation was attributable to characteristics of the imaging center.

Ambulatory Care Facilities↗
PubMed1999

Efficacy of antiseptic-impregnated central venous catheters in preventing catheter-related bloodstream infection: a meta-analysis.

CONTEXT: Central venous catheters impregnated with chlorhexidine and silver sulfadiazine have recently been introduced for the prevention of catheter-related infections. However, there remains some uncertainty regarding the efficacy of these catheters because of conflicting reports in the literature. OBJECTIVE: To evaluate the efficacy of chlorhexidine-silver sulfadiazine-impregnated central venous catheters in the prevention of catheter-related bloodstream infection. DATA SOURCES: Studies identified from a computerized search of the MEDLINE database from January 1966 to January 1998, reference lists of identified articles, and queries of principal investigators and the catheter manufacturer. STUDY SELECTION: Randomized trials comparing chlorhexidine-silver sulfadiazine-impregnated central venous catheters with nonimpregnated catheters were included. The outcomes assessed were catheter colonization and catheter-related bloodstream infection confirmed by catheter culture. DATA EXTRACTION: Twelve studies met the inclusion criteria for catheter colonization and included a total of 2611 catheters. Eleven studies with a total of 2603 catheters met the inclusion criteria for catheter-related bloodstream infection. Most patients in these studies were from groups considered to be at high risk for catheter-related infections. Summary statistics were calculated using Mantel-Haenszel methods under a fixed-effects model. DATA SYNTHESIS: The summary odds ratio for catheter colonization was 0.44 (95% confidence interval [CI], 0.36-0.54; P<.001), indicating a significant decrease in catheter colonization associated with impregnated catheters. The studies examining the outcome of primary interest, catheter-related bloodstream infection, had a summary odds ratio of 0.56 (95% CI, 0.37-0.84; P = .005). CONCLUSIONS: Central venous catheters impregnated with a combination of chlorhexidine and silver sulfadiazine appear to be effective in reducing the incidence of both catheter colonization and catheter-related bloodstream infection in patients at high risk for catheter-related infections.

Anti-Infective Agents, Local↗
PubMed1998

Predicting patients' utilities from quality of life items: an improved scoring system for the UBQ-H.

The Utility-based Quality of Life--Heart Questionnaire (UBQ-H) is a cardiovascular extension of the Health Measurement Questionnaire. It is a multidimensional instrument that can be scored to yield a utility estimate using the Rosser Index and a classification algorithm developed for the Health Measurement Questionnaire. The aim of this study was to employ a statistical modelling approach to devise an improved scoring system. A sample of 201 cardiovascular patients completed the UBQ-H and assessed the utility of their own health state using standard gamble and time trade-off questions in an interview. Two new scoring methods were devised by regressing the UBQ-H data against patients' self-assessed utilities. The new methods gave utility estimates that correlated with angina/dyspnoea grades, life satisfaction scores and General Health Questionnaire (GHQ) scores. In a second sample of 1,112 cardiovascular patients, the UBQ-H utilities were able to distinguish between patients who had/had not experienced an adverse event (e.g. myocardial infarction) and were responsive to changes in health over time. The new scoring methods were not particularly more sensitive to quality of life effects than the original method based on the Rosser Index. However, they produced significantly lower estimates and more accurately reflected patients' self-assessed utilities.

Cardiovascular Diseases↗
PubMed1998

A comparison of dressings in the management of surgical abdominal wounds.

This prospective randomised trial compared the performance of three dressing protocols in the management of 36 dehisced surgical abdominal wounds: a standard alginate; a gauze moistened with sodium hypochlorite (0.05%); and a combine dressing pad. Outcomes assessed were: healing time (cm2 per day and cm3 per day), patient comfort (pain and satisfaction) and cost. There were no statistically significant differences in healing rates between the three groups but there was a trend for the combine dressing pad protocol to produce a greater reduction in wound area. The combine dressing pad protocol performed well when compared with the calcium alginate in terms of healing time, patient comfort and cost. Maximum pain was significantly greater (p = 0.011) and satisfaction significantly lower among patients who received the sodium hypochlorite protocol. Costs during the in-patient phase were also substantially higher for the sodium hypochlorite protocol. Trial results support the view that sodium hypochlorite dressing protocols for surgical wounds should be abandoned.

Aged↗
PubMed1997

First- and second-year effects in trials of calcium supplementation on the loss of bone density in postmenopausal women.

The analysis of clinical trials investigating the effect of calcium on the loss of bone mass or density has been based on the assumption that the effects are the same for all years of follow-up. Hence the average annual rate of loss is calculated and compared in the calcium and control groups. In this metaanalysis, we investigated this assumption and found that it is not tenable in the groups randomized to calcium for most sites that have been measured. The rate of bone loss was significantly less in the first year after randomization than in the second year. By contrast, the rate of loss in the control groups was less in the second year than the first, although this was not significant. At the spine, femoral neck, trochanter, intertrochanter, midtibia, and ultratibia, the effect of calcium in reducing bone loss was statistically significant compared with control only in the first year after randomization; there was no difference in rates between the groups in the second year. The effect of calcium compared to control in two arm sites and Ward's triangle was of a similar magnitude but was not statistically significant. We recommend that analysis and metaanalysis of trials should always consider the effects on a year-by-year basis.

Bone Density↗
PubMed1997

Improved quality of life with megestrol acetate in patients with endocrine-insensitive advanced cancer: a randomised placebo-controlled trial. Australasian Megestrol Acetate Cooperative Study Group.

PURPOSE: To investigate the effect of two doses of megestrol acetate (MA) compared with placebo on quality of life (QoL) and nutritional status (NS) in patients with advanced endocrine-insensitive cancer. PATIENTS AND METHODS: Two hundred forty patients were randomised to double-blind MA 480 mg/day, MA 160 mg/day, or matching placebo for 12 weeks. Nutritional status (including weight, skinfold thickness and midarm circumference) and QoL (using 6 linear analogue self-assessment (LASA) scales) were assessed at randomisation and after four, eight and 12 weeks. A QoL ranking incorporating QoL and death was also used ranging from 1 = dead to 5 = much better QoL. RESULTS: One hundred seventy-four patients were assessable at week four, 136 at week eight and 103 patients at week 12. Patients receiving MA reported substantially better appetite (P = 0.001), mood (P = 0.001) and overall quality of life (P < 0.001), and possibly less nausea and vomiting (P = 0.08) than patients receiving placebo, based on a test for trend. A larger benefit was seen with the higher dose which (unlike the lower dose) was significantly better in pairwise comparisons with placebo for appetite, mood and overall QoL (each P < or = 0.001). Despite some missing data on QoL scores, QoL ranking was available on 227 (95%) of patients with significantly higher QoL ranking associated with MA (P = 0.002). Improvements in QoL occurred early within four weeks and were sustained. No statistically significant differences were observed in NS measurements, including weight (P = 0.29). Side effects of therapy were minor and did not differ significantly across treatments. CONCLUSION: Megestrol acetate given at 480 mg/day is useful palliation in patients with endocrine-insensitive advanced cancer. It improves appetite, mood and overall quality of life in these patients, although not through a direct effect on nutritional status.

Aged↗
PubMed1996

Angiographic severity of coronary narrowing is a surrogate marker for the extent of coronary atherosclerosis.

Most acute coronary events occur because of narrowings at sites of angiographically minor plaque. Despite this, angiograms are reported in terms of the number of coronary arteries with severe narrowings. Disease severity is correlated with prognosis, but this may simply be due to a strong positive correlation between the severity and extent of coronary atheroma. We therefore aimed to assess the relation between the severity and the extent of coronary atherosclerosis. Coronary angiograms of 350 consecutive patients referred for elective cardiac catheterization were analyzed. Two independent observers calculated the number of arteries with > or = 70% stenosis, a disease severity score, and an extent score (percentage of the coronary artery length with any luminal irregularity). There were no obstructive stenoses in 123 patients (35%); 91 (26%) had 1-vessel disease, 81 (23%) had 2-vessel disease, and 55 (16%) had 3-vessel coronary artery disease. The median severity score was 1 (lower, upper quartile 0, 3; range 0 to 8), and the median extent score was 66% (lower, upper quartile 32, 83; range 0% to 100%). There was a strong linear relation between severity score and extent score (r = 0.62, p < 0.001); however, the data were better described by 2 intersecting straight lines, with a steeper increase in disease severity when the extent score was between 80% and 90% (F1;121 = 6.9, p = 0.001). The severity of coronary disease is therefore significantly correlated with disease extent. This may explain the observed relation between the number of arteries with obstructive stenoses and subsequent risk, even though most events occur at sites of minor plaque.

Adult↗
PubMed1996

In vitro and in vivo assessment of urethral warming catheters for the transperineal cryoablation of prostatic carcinoma.

OBJECTIVE: To evaluate the two most common urethral warming catheters currently available for their effectiveness in preventing urethral injury in an animal model and thus during transperineal cryosurgery for the treatment of prostate cancer. PATIENTS, MATERIALS AND METHODS: The warming efficiency of the variable-diameter thin latex-balloon catheter (Cook, Australia) and the fixed-diameter PVC catheter (Candela, USA) were evaluated in a water-bath. A sheep model was then used for subsequent experiments to further evaluate the better catheter. The technique used for the insertion of the Cook catheter in a series of 33 patients treated with prostate cryosurgery is also described. RESULTS: In vitro, the Cook catheter was more effective (P < 0.01) than the Candela catheter in preventing localized cooling. In vivo, results in five animals showed that the urethral epithelium was viable in all sections that had been protected by the catheter and focally denuded or necrotic in those sections not protected, with each animal used as its own control (P < 0.01 Fisher's exact test). The 33 patients treated while using the Cook catheter had no subsequent complications. CONCLUSION: The urethral warming catheter currently in use for prostatic cryosurgery in Australia is more effective in vitro than its competitor and is effective in preventing urethral injury in vivo.

Catheterization↗
PubMed1996

Generalized estimating equations for ordinal data: a note on working correlation structures.

Generalized estimating equations (Liang, K. Y. and Zeger, S., 1986, Biometrika 73, 13-22) allow longitudinal or clustered data to be modeled with minimal assumptions about their dependence structures. Association structures for polytomous data have generally required the estimation of a large number of parameters. In many applications involving repeated categorical data, an ordinal structure is present. A range of association structures and computational methods for ordinal categorical data is described, based on the cumulative odds ratio, which allows much more parsimonious models. This permits the generalized estimating equation methodology to be used for smaller sets of ordinal data and with less effort expended on modeling associations. The method is illustrated on sets of ordinal data from medical studies.

Adult↗
PubMed1995

A simple and effective way to reduce postoperative pain after laparoscopic cholecystectomy.

The aims of this study were to see if laparoscopic cholecystectomy is associated with a similar postoperative pain pattern to gynaecological laparoscopy and to see whether the use of a suprahepatic suction drain makes recovery from laparoscopic cholecystectomy more comfortable. After routine laparoscopic cholecystectomy and insertion of a suprahepatic suction drain, patients were randomized to suction or no suction on the drain. The time course of the severity of wound, abdominal and shoulder tip pain was assessed by visual analogue scales administered in the morning and afternoon of the first 3 postoperative days. The control group had a high incidence of shoulder tip pain similar to that after gynaecological laparoscopy. Patients in the treatment group reported significantly less shoulder tip pain than the control group (O.R. 0.16, 95% CI, 0.06-0.40). There was a tendency for the treatment group to report reduced abdominal and, to a lesser extent, wound pain. The authors recommend suprahepatic suction as a simple and more effective way to improve patient comfort after laparoscopic cholecystectomy.

Abdominal Pain↗