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Biomedical subjects

George Tomlinson

Publications and source records attributed to George Tomlinson.

At least 19 recordsLinked to original sources
PubMed2006

Responsiveness of disease-specific and generic utility instruments in prostate cancer patients.

BACKGROUND: Preferences (utilities) for health outcomes have an important role in decisions about prostate cancer screening and treatment. The responsiveness of utility instruments has not been evaluated. SUBJECTS: Prostate cancer outpatients from the Princess Margaret Hospital, Toronto (n = 248) were allocated into three cohorts: N - newly diagnosed and treated; M - metastatic disease; O - all others. MEASURES: We measured quality of life at 3 points within 12 months using 3 disease-specific utility instruments (Patient Oriented Prostate Utility Scales), 3 generic utility instruments (Health Utilities Index, EQ-5D, Quality of Well-Being Scale), and 3 profile scales (PORPUS-P profile, Prostate Cancer Index, QLQ-C-30). Responsiveness was assessed using measures of internal responsiveness (standardized effect size, standardized response mean) and external responsiveness (receiver operator curve analysis, mixed model regression). RESULTS: Cohort N patients showed post-treatment declines followed by improvement in global health and functional status. Disease specific instruments detected moderate (0.4-1.3) decrements followed by small increments (0.1-0.4) in standardized effect size and standardized response mean. Most instruments detected change using external responsiveness measures (all cohorts). CONCLUSIONS: Disease-specific utility instruments appeared to be more responsive than generic instruments. Use of generic instruments should be supplemented with a responsive disease-specific instrument, particularly for applications in early prostate cancer.

Aged↗
PubMed2006

Menstrual and reproductive risk factors and risk for gastric adenocarcinoma in women: findings from the canadian national enhanced cancer surveillance system.

PURPOSE: The role of menstrual and reproductive risk factors for gastric cancer has not been well studied. METHODS: This population-based case-control study included 326 women aged 20 to 74 years with gastric adenocarcinoma. Controls were 326 women frequency matched on age. Data for reproductive and/or hormonal exposure and gastric cancer risk factors were captured through self-administered questionnaire. RESULTS: Later age at menarche was associated with increased risk for adenocarcinoma compared with menarche onset at younger than 13 years of age (13 to 14 years: odds ratio [OR], 1.45; 95% confidence interval [CI], 1.00-2.10; > or =15 years: OR, 1.93; 95% CI, 1.19-3.13). Compared with premenopause, natural menopause was associated with increased risk for adenocarcinoma (OR, 1.99; 95% CI, 0.98-4.05). Compared with nulliparity, 4 or more births were associated with decreased risk for gastric cancer, as was being pregnant for 5 months or longer if the first pregnancy occurred at younger than 24 years (OR, 0.55; 95% CI, 0.31-0.96) or 25 years or older (OR, 0.67; 95% CI, 0.38-1.18). Oral contraceptives and hormone replacement therapy were associated with a non-statistically significant decreased risk. CONCLUSION: These findings suggest that hormonal factors associated with greater exposure to estrogen and/or progesterone may be associated with decreased risk for gastric cancer.

Adenocarcinoma↗
PubMed2006

The effect of dairy product ingestion on human immunodeficiency virus-related diarrhea in a sample of predominantly gay men: a randomized, controlled, double-blind, crossover trial.

BACKGROUND: In the highly active antiretroviral therapy (HAART) era, chronic diarrhea remains common in human immunodeficiency virus (HIV) illness. Empirical lactose avoidance is often advised despite lack of evidence of benefit in a population at risk for osteopenia and malnutrition. METHODS: The a priori hypothesis was that moderate lactose ingestion would not worsen diarrhea in this population. We used a double-blind, noninferiority, randomized crossover trial in a community setting of primary and tertiary care HIV clinics. The participants all had chronic diarrhea and were a volunteer sample of 49 predominantly white HIV-infected men who have sex with men. They ingested 240 mL of low-fat milk (12 g of lactose) and lactose-free milk during 2 separate study periods. The primary outcome was mean difference in stool weight between the 2 study periods in the 8 hours after milk ingestion. Lactose was judged not to worsen diarrhea if this difference did not exceed 167 g in 8 hours with 95% certainty. RESULTS: Forty-eight (98%) of 49 participants were male. Median age, CD4 cell count, and viral load were 42 years (range, 20-62 years), 390 cells/mL (range, 20-1100 cells/mL), and 112 copies/mL (range, <50 to >500,000 copies/mL), respectively. Thirty-nine participants (80%) were taking HAART medication. Ten participants (20%) were lactase deficient. The mean difference in stool weight between the 2 study periods was -41.3 g/8 h (upper 95% confidence limit, -13.5 g) for the entire group and +11.3 g/8 h (upper 95% confidence limit, +47.4 g) for the lactase-deficient group. CONCLUSIONS: Moderate lactose ingestion does not worsen diarrhea in HIV-infected persons with chronic diarrhea, regardless of lactase status. Therefore, avoidance of modest quantities of milk may not be justified in this population.

Adult↗
PubMed2006

Two-year outcomes, health care use, and costs of survivors of acute respiratory distress syndrome.

RATIONALE: Little is known about the long-term outcomes and costs of survivors of acute respiratory distress syndrome (ARDS). OBJECTIVES: To describe functional and quality of life outcomes, health care use, and costs of survivors of ARDS 2 yr after intensive care unit (ICU) discharge. METHODS: We recruited a cohort of ARDS survivors from four academic tertiary care ICUs in Toronto, Canada, and prospectively monitored them from ICU admission to 2 yr after ICU discharge. MEASUREMENTS: Clinical and functional outcomes, health care use, and direct medical costs. RESULTS: Eighty-five percent of patients with ARDS discharged from the ICU survived to 2 yr; overall 2-yr mortality was 49%. At 2 yr, survivors continued to have exercise limitation although 65% had returned to work. There was no statistically significant improvement in health-related quality of life as measured by Short-Form General Health Survey between 1 and 2 yr, although there was a trend toward better physical role at 2 yr (p = 0.0586). Apart from emotional role and mental health, all other domains remained below that of the normal population. From ICU admission to 2 yr after ICU discharge, the largest portion of health care costs for a survivor of ARDS was the initial hospital stay, with ICU costs accounting for 76% of these costs. After the initial hospital stay, health care costs were related to hospital readmissions and inpatient rehabilitation. CONCLUSIONS: Survivors of ARDS continued to have functional impairment and compromised health-related quality of life 2 yr after discharge from the ICU. Health care use and costs after the initial hospitalization were driven by hospital readmissions and inpatient rehabilitation.

Adult↗
PubMed2006

The validity of the certification of manner of death by Ontario coroners.

PURPOSE: The aim of the study is to examine the validity of manner of death (MOD) certification of unnatural adult deaths by Ontario coroners. METHODS: A census of 306 active coroners practicing in Ontario was performed, with data collection occurring in 2002. Mailed self-administered questionnaires contained 14 fictitious clinicopathologic scenarios and questions regarding demographic information of the coroner. Crude and adjusted odds ratios of correct MOD certification were calculated by using responses of two deputy chief coroners as the gold standard. RESULTS: Nearly 74% of coroners responded to the survey. Deaths from hanging, drowning, and carbon monoxide had better odds of being certified correctly; whereas deaths from heroin, over-the-counter medication, and injuries from a descent had decreased odds of being certified correctly. Scenarios including a prior suicide attempt or a note had greater odds of correct MOD certification than those with only depression. Accidental deaths were underreported when injury resulted in a "natural" lethal complication and when there was a delay between injury and death. CONCLUSIONS: In detailing which deaths are likely to be misclassified and how they may be misclassified, this study will allow future research to more accurately assess suicidal and accidental deaths.

Cause of Death↗
PubMed2006

Utility-based Quality of Life measures in Alzheimer's disease.

OBJECTIVES: To explore whether Alzheimer's disease patients could rate their quality of life (QOL) using utility-based health indexes, and to provide new knowledge about the measurement properties of these instruments for patient and caregiver proxy ratings. METHODS: A convenience sample of 60 mild-moderate AD patients and their caregivers were randomized to complete the Quality of Well-Being Scale (QWB), Health Utilities Index (HUI3) or EQ-5D and visual analogue scale (VAS) on two occasions. Test-retest reliability (intraclass correlation coefficients) and convergent validity (Spearman correlations) of utility scores with global health status, activities of daily living, comorbidity, mood, cognition and other utility measures were assessed. RESULTS: Completion time was shortest for the combined EQ-5D and VAS. For patients with mild dementia and for proxies, reliability was >or= 0.70 for the EQ-5D, QWB and HUI3. The EQ-5D had a ceiling effect for patient ratings. Convergent validity was demonstrated for patient and proxy ratings, with the strongest validity for EQ-5D ratings and the weakest validity for HUI3 patient ratings. Mean patient utility scores were significantly higher than mean proxy scores for all measures (p<0.001). CONCLUSIONS: For patient and proxy ratings, the EQ-5D had the best combination of measurement properties, although it had a substantial ceiling effect for patient ratings. Proxy QOL ratings did not accurately reflect patients' ratings.

Activities of Daily Living↗
PubMed2006

An unadjusted NNT was a moderately good predictor of health benefit.

BACKGROUND AND OBJECTIVE: Whether the number needed to treat (NNT) is sufficiently precise to use in clinical practice remains unclear. We compared unadjusted NNTs to quality-adjusted life years (QALYs) gained, a more comprehensive measures of health benefit. STUDY DESIGN AND SETTING: From a subset (n = 65) of a dataset of 228 cost-effectiveness analyses, we compared how well NNTs predicted clinically important QALY gains using correlation analysis, multivariable models and receiver-operator curve (ROC) analysis. RESULTS: NNT was inversely correlated with QALY gains (P < .001); this relationship was affected by quality of life and life-expectancy gains of treatment (P 15 had a sensitivity of 82% to 100%. For ruling in therapies with high QALY gains (threshold >or=0.125 to >or=0.5 QALYs), an NNT 15 to rule in and out therapies with large QALY gains may provide general guidance regarding the magnitude of health benefit.

Cost-Benefit Analysis↗
PubMed2006

Rethinking 30-day mortality risk after radical prostatectomy.

OBJECTIVES: Although radical prostatectomy (RP) is associated with greater 30-day mortality in older men, the magnitude of the excess risk in older age groups compared with younger ones has not been well characterized. METHODS: Using data from the Ontario Cancer Registry, we identified 11,010 men who underwent RP from 1990 to 1999 in Ontario, Canada and compared the 30-day mortality risk immediately after RP with the 1-month mortality risk in the same population of men 7 to 12 months after RP and that of an age-matched general population of men. RESULTS: Overall, 53 men (0.48%) died within 30 days of surgery. The absolute excess 30-day mortality risk associated with RP was 0.18%, 0.51%, and 0.59% for men aged 50 to 59, 60 to 69, and 70 to 79 years, respectively, and was similar for men aged 60 to 69 and 70 to 79 years (P >0.05). The relative mortality risk within 30 days of RP was approximately nine times the baseline risk (95% confidence interval 3 to 38) and was similar for men in all three age groups (P >0.05). CONCLUSIONS: The results of our study indicate that men aged 70 to 79 years do not have a greater absolute excess or relative risk of 30-day mortality after RP compared with men aged 60 to 69 years.

Aged↗
PubMed2006

Short-term daily or weekly administration of micronutrient Sprinkles has high compliance and does not cause iron overload in Chinese schoolchildren: a cluster-randomised trial.

OBJECTIVES: To examine consumption rates and serum ferritin (SF) concentrations (as a marker of safety) among schoolchildren (3-6 years) provided with daily and weekly micronutrients. DESIGN AND METHODS: Micronutrients were provided for one school term (13 weeks) to a kindergarten in northern China as single-dose Sprinkles sachets containing 30 mg of iron as encapsulated ferrous fumarate, 5 mg zinc gluconate, 50 mg vitamin C, 300 microg vitamin A, 7.5 microg vitamin D3 and 150 microg folic acid. Sixteen classrooms were randomly assigned to: (1) daily supplements for 5 days a week (daily group); (2) weekly supplements (weekly group); or (3) no supplements (control group). Consumption of sachets was monitored for each child and SF concentrations were measured at the end of study. Random effects general linear models and graphs were used to compare the groups. RESULTS: A total of 415 children from 16 classrooms entered the study. At the end of the study, mean consumption rates per child were 86% (daily group; standard deviation (SD) 12%) and 87% (weekly group; SD 16%). Median SF concentrations were 71 microg l(-1) (range 27-292 microg l(-1); daily group), 55 microg l(-1) (range 11-299 microg l(-1); weekly group) and 54 microg l(-1) (range 7-327 microg l(-1); control group); the overall difference was not significant (P=0.06). However, the daily group was significantly different from the control (P=0.02); daily and weekly groups had higher SF at lower percentiles and similar SF at higher percentiles compared with the control group. CONCLUSION: The high consumption rates and appropriate SF concentrations in the supplemented groups suggest that a short-term school programme with Sprinkles is an efficient and safe way to provide micronutrients (including iron).

Administration, Oral↗
PubMed2006

Physiologic mechanisms can predict hematologic responses to iron supplements in growing children: a computer simulation model.

BACKGROUND: Iron deficiency is the most common preventable nutrition problem in developing countries. Several randomized clinical trials (RCTs) have been conducted to determine the effectiveness of various iron dosing schemes in multiple settings. OBJECTIVE: The objective was to determine whether enough is known about iron metabolism to predict hemoglobin and serum ferritin (SF) concentrations with a computer model and whether the model could be used as a substitute for new RCTs. DESIGN: Guided by the physiology of iron absorption and regulation, we used data from RCTs that tested iron Sprinkles to develop a computer model. Of 2 RCTs in Ghana, we used 1 to compute the amount of iron absorbed from a given dose in anemic and nonanemic children and the other to compute the resulting change in hemoglobin concentrations. We used this model to predict hemoglobin and SF concentrations in a new RCT in China and compared model-predicted values with actual values by using summary statistics (means and medians) and quantile-quantile plots. RESULTS: The model-predicted hemoglobin means were within +/-2 g/L, and SF medians were within +/-3 microg/L of the corresponding means and medians of the actual values. On quantile-quantile plots, the predicted hemoglobin quantiles were within +/-5 g/L, and SF quantiles were within +/-10 microg/L of the corresponding quantiles of the actual values. CONCLUSION: Our model of iron metabolism can accurately predict hemoglobin and SF concentrations after iron supplementation with Sprinkles in children; the model can thus obviate the need for repeating RCTs in multiple settings.

Anemia, Iron-Deficiency↗
PubMed2006

Factors affecting perioperative transfusion decisions in patients with coronary artery disease undergoing coronary artery bypass surgery.

BACKGROUND: A high proportion of patients having cardiac bypass surgery receive erythrocyte transfusions. Decisions about when to transfuse patients having surgery for coronary artery disease may impact on erythrocyte utilization and patient morbidity and mortality. There are no published data about the factors that influence physicians' decisions to transfuse erythrocytes to these patients. The objectives of this study were to determine the hemoglobin concentration for transfusion and the factors that influence physicians' perioperative transfusion decisions for coronary artery bypass patients. METHODS: The authors conducted a cross-sectional study using pretested, self-administered, mailed questionnaires sent in 2004 to all cardiac surgeons and anesthesiologists in Canada who participate in coronary artery bypass surgery. The questionnaire included four intraoperative and four postoperative vignettes. Factors assessed included patient age, sex, cardiac index, and myocardial ischemia. RESULTS: The response rates were 70% (345 of 489) for the intraoperative and 61% (297 of 489) for the postoperative case scenarios. The mean hemoglobin concentrations for transfusion were 7.0 g/dl for the intraoperative case scenarios and 7.2 g/dl for the postoperative case scenarios. Older age, the presence of myocardial ischemia, and a low cardiac index were factors that increased the hemoglobin concentration for transfusion (P < 0.0001). Physicians ranked myocardial ischemia as the most significant factor affecting their transfusion decisions. CONCLUSIONS: Factors such as the presence of a low cardiac index, myocardial ischemia, and older age increase the hemoglobin concentrations at which physicians transfuse coronary bypass surgery patients. Future studies are required to elucidate whether transfusions based on these variables affect patient morbidity and mortality.

Adult↗
PubMed2006

Cartilage T2 assessment: differentiation of normal hyaline cartilage and reparative tissue after arthroscopic cartilage repair in equine subjects.

PURPOSE: To prospectively assess T2 mapping characteristics of normal articular cartilage and of cartilage at sites of arthroscopic repair, including comparison with histologic results and collagen organization assessed at polarized light microscopy (PLM). MATERIALS AND METHODS: Study protocol was compliant with the Canadian Council on Animal Care Guidelines and approved by the institutional animal care committee. Arthroscopic osteochondral autograft transplantation (OAT) and microfracture arthroplasty (MFx) were performed in knees of 10 equine subjects (seven female, three male; age range, 3-5 years). A site of arthroscopically normal cartilage was documented in each joint as a control site. Joints were harvested at 12 (n = 5) and 24 (n = 5) weeks postoperatively and were imaged at 1.5-T magnetic resonance (MR) with a 10-echo sagittal fast spin-echo acquisition. T2 maps of each site (21 OAT harvest, 10 MFx, 12 OAT plug, and 10 control sites) were calculated with linear least-squares curve fitting. Cartilage T2 maps were qualitatively graded as "organized" (normal transition of low-to-high T2 signal from deep to superficial cartilage zones) or "disorganized." Quantitative mean T2 values were calculated for deep, middle, and superficial cartilage at each location. Results were compared with histologic and PLM assessments by using kappa analysis. RESULTS: T2 maps were qualitatively graded as organized at 20 of 53 sites and as disorganized at 33 sites. Perfect agreement was seen between organized T2 and histologic findings of hyaline cartilage and between disorganized T2 and histologic findings of fibrous reparative tissue (kappa = 1.0). Strong agreement was seen between organized T2 and normal PLM findings and between disorganized T2 and abnormal PLM findings (kappa = .92). Quantitative assessment of the deep, middle, and superficial cartilage, respectively, showed mean T2 values of 53.3, 58.6, and 54.9 msec at reparative fibrous tissue sites and 40.7, 53.6, and 61.6 msec at hyaline cartilage sites. A significant trend of increasing T2 values (from deep to superficial) was found in hyaline cartilage (P < .01). Fibrous tissue sites had no significant change with depth (P > .59). CONCLUSION: Qualitative and quantitative T2 mapping helped differentiate hyaline cartilage from reparative fibrocartilage after cartilage repair at 1.5-T MR imaging.

Animals↗
PubMed2006

Enhancing component on CT to predict malignancy in cystic renal masses and interobserver agreement of different CT features.

OBJECTIVE: The objective of our study was to determine the CT features of complex cystic renal masses that are the most predictive of malignancy and to assess interobserver variability when interpreting these features. MATERIALS AND METHODS: Two radiologists blinded to pathology results retrospectively reviewed CT scans of 36 consecutive cystic renal masses in 30 patients (19 men and 11 women; age range, 28-76 years; mean age, 59 +/- 13 years) who had undergone surgery. The study population included only masses with a cystic component on gross pathology and imaging. All patients underwent contrast-enhanced CT. The reviewers recorded the CT features of each cystic mass, including the presence of enhancing components. Accuracy values and odds ratio to predict malignancy were calculated for each CT feature. Weighted kappa was used to measure interobserver agreement. RESULTS: There were 21 cystic renal cell cancers and 11 benign cystic lesions. All cystic renal cell carcinomas showed an enhancing septal or nodular component. The mean sensitivity and specificity of the two reviewers in predicting malignancy for the presence of septal enhancement were 83% (95% confidence interval [CI], 65-93%) and 82% (95% CI, 56-94%); for nodular enhancement, 67% (95% CI, 49-81%) and 96% (95% CI, 75-99%); and for either septal or nodular enhancement, 100% (95% CI, 86-100%) and 86% (95% CI, 67-95%), respectively. The interobserver agreements for septal and nodular enhancement were good (kappa = 0.67) and moderate (kappa = 0.57), respectively. CONCLUSION: The presence of either nodular or septal enhancement shows the highest sensitivity for predicting malignancy with moderate to good interobserver agreement.

Adult↗
PubMed2006

Long-term effects of a diabetes and pregnancy program: does the education last?

OBJECTIVE: To determine whether women with pregestational diabetes obtained long-term benefits from an intensive diabetes management program during pregnancy. RESEARCH DESIGN AND METHODS: Women with pregestational diabetes who had attended an intensive diabetes management program in pregnancy between 1991 and 1999 were interviewed regarding diabetes self-management behaviors and current glycemic control. A retrospective chart review was done to obtain information on self-management behaviors at entry to the program and at delivery and compared with the present. RESULTS: Comparing entry to the program to delivery, all diabetes self-management behaviors improved significantly, including frequency of self-monitoring of blood glucose, frequency of insulin injections, and frequency and complexity of insulin dose adjustment (IDA). HbA(1c) (A1C) also improved significantly from entry to delivery (mean 0.073-0.060) (P < 0.0001). Comparing entry to the present, frequency of insulin injections improved significantly (P = 0.0004), frequency of IDA improved significantly (P = 0.004), and complexity of IDA improved significantly (P = 0.0032). However, there was no significant change in frequency of self-monitoring of blood glucose (P = 0.766) from before pregnancy to the present, and A1C significantly worsened by 0.015 (P < 0.0001, 95% CI 0.009-0.021) from entry to the program to the present. CONCLUSIONS: Women participating in an intensive diabetes management program during pregnancy improve significantly from entry to delivery in diabetes self-management behaviors and glycemic control and, in the long term, retain some of these behaviors and knowledge. However, this is not reflected in an improved A1C level. This may be explained by the loss of contact with the diabetes care team and/or the discontinuation of frequent self-monitoring of blood glucose-a critical behavior necessary for achieving optimal glycemic control.

Adult↗
PubMed2006

Complications of embolization of arteriovenous malformations of the brain.

OBJECT: The goal of this study was to determine the rates of mortality and morbidity associated with the embolization of arteriovenous malformations (AVMs) of the brain and to analyze the factors related to embolization-related complications. METHODS: The University of Toronto Brain Vascular Malformation Study Group database was reviewed. Three hundred six patients underwent 513 embolization sessions between November 1984 and September 2002. The combined rate of death and any permanent disabling neurological deficit was 3.9% per patient. Location of the AVM in an eloquent part of the brain, presence of a fistula, and a venous deposition of glue were related to complications. A clinically important reduction in the rate of death and disabling morbidity occurred in the second half of the study period. CONCLUSIONS: Embolization of AVMs in the brain is associated with low overall rates of mortality and disabling morbidity.

Adolescent↗
PubMed2006

Sonographic diagnosis of gestational trophoblastic disease and comparison with retained products of conception.

OBJECTIVE: Gestational trophoblastic disease (GTD) and retained products of conception (RPC) can be difficult to distinguish sonographically. The aim of this study was to determine whether there were any sonographic criteria that could prospectively distinguish one from the other. METHODS: Institutional ethics approval was obtained, and acquisition of consent was waived by the Institutional Review Board. A retrospective review of gynecologic oncology and pathology databases identified 17 cases of GTD and 14 cases of RPC. Findings from the pre-evacuation transvaginal sonographic examinations were analyzed. The scans were independently reviewed by 2 senior radiologists with specific expertise in pelvic sonography using several predetermined sonographic features. The reviewers were blinded to the diagnosis. A consensus reading was obtained. RESULTS: The sonographic features that predicted GTD were a myometrial epicenter (P = .0002; odds ratio [OR] = 28), depth of myometrial invasion of more than one third (P = .001; OR = 20), placental venous lakes (P = .04; OR = 9), maximum mass dimensions of more than 3.45 cm (P = .009), and maximum endometrial thickness of less than 12 mm (P = .02). The remaining criteria were not statistically significant and included the characteristics of the mass, ascites, a "snowstorm" appearance, mass vascularity (including resistive index and peak systolic velocity), and the presence of ovarian cysts. CONCLUSIONS: There are specific transvaginal sonographic features that can accurately differentiate GTD and RPC.

Abortion, Incomplete↗
PubMed2006

Decision analysis in aerospace medicine: costs and benefits of a hyperbaric facility in space.

INTRODUCTION: Assembly and maintenance of the International Space Station (ISS) requires an unprecedented number of spacewalks, which expose astronauts to the risk of decompression sickness (DCS). We illustrate the use of decision analysis to compare a hyperbaric oxygen (HBO) chamber to currently available therapy for DCS treatment on the ISS. METHODS: A decision-analytic model that simulates events over the lifespan of the ISS was constructed. Inputs to the model for probabilities, costs, and measures of morbidity and mortality were derived from a variety of sources, including a systematic literature review and an iterative consultation process with personnel at the Canadian Space Agency and the National Aeronautics and Space Administration (NASA). The decision model was analyzed using the methods of Monte-Carlo simulation and expected value calculation. Main outcome measures included the present value of costs and quality adjusted life years (QALYs), and the cumulative probability of mission-related events over the life cycle of the ISS. Sensitivity analysis was performed. RESULTS: The HBO chamber strategy is associated with a mean cost of -12.5 million dollarsw (a net cost saving of 12.5 million dollars) with a 95% CI (-112.8 million dollars, 51.3 million dollars). An HBO chamber reduces the likelihood of a premature shuttle return and a premature Soyuz return by 8% and 3%, respectively. The result is sensitive to the lifespan of the ISS. CONCLUSIONS: At a 50 million dollars cost, an HBO chamber is likely, though not certain, to result in cost savings. Decision analysis is a useful tool for use in priority setting in aerospace medicine.

Cost-Benefit Analysis↗