PubMed Health⌕ Search

Biomedical subjects

Boris Sobolev

Publications and source records attributed to Boris Sobolev.

14 recordsLinked to original sources
PubMed2006

The direct costs of HIV/AIDS care.

We reviewed published studies reporting the direct medical costs of treating HIV-infected people in countries using highly active antiretroviral therapy (HAART). Of 543 potentially relevant studies, only nine provided adequate data to make a meaningful statement about costs. Within studies, people with more advanced disease incurred higher total costs. Valid comparisons of total direct medical costs between studies were not possible because of differences in the specific components included, the heterogeneous nature of study populations in terms of disease stage, the sources and methods used to estimate unit costs, and the level of aggregation at which results were reported. The advent of HAART has major implications for the cost of treating HIV-infected individuals. Although this information is important for planning purposes, only a small number of published studies provide useful estimates of the direct cost. A useful method of estimating resource use and costs is computer simulation.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Prediction of protein functional specificity without an alignment.

We propose a new approach to predict functional specificity of proteins from their amino acid sequences. Our approach is based on two things: structural Multilevel Neighborhoods of Atom (MNA) descriptors and an original Bayesian algorithm. Usually, a protein sequence is presented as a string of amino acid symbols. Here we introduce a new description of an amino acid sequence: a set of structural MNA descriptors. The MNA descriptor is a string describing an atom and its neighbor atoms according to the selected level. In this work, we also use description of a protein sequence as a set of peptides (strings of amino acid symbols). We performed a case study on two subsubclasses of enzyme nomenclature (EC). It is shown that B-statistics give a sufficient predictive power of enzyme specificity prediction for both MNA descriptors and peptides. We also showed that MNA descriptors give higher accuracy values in comparison with peptides and also provide a choice of MNA descriptor levels for best accuracy prediction. The highest average accuracy prediction that was achieved was 0.98.

Amino Acid Sequence↗
PubMed2006

Delays worsen quality of life outcome of primary total hip arthroplasty.

Although there are indications of health status deterioration for patients while waiting for elective total hip arthroplasties, controversy exists regarding the effect of waiting on postoperative outcomes. We hypothesized that longer waiting times are detrimental to achieving the full benefit of surgery. We prospectively examined 201 patients with osteoarthritis who were on the waiting list for primary total hip arthroplasties. The Western Ontario and McMaster Universities Osteoarthritis Index questionnaire was used to assess patients at surgical consultation (preoperative) and 1 year postoperative. The study included regression models to determine the expected outcome for an individual's preoperative score. Logistic regression models were used to assess the relationship between waiting time and the probability of a better than expected outcome. We found that the odds of achieving a better than expected postoperative functional outcome decreased by 8% for each month on the waiting list. Expedited access resulted in a larger proportion of patients with better than expected function 12 months after surgery.

Adult↗
PubMed2006

Does wait-list size at registration influence time to surgery? Analysis of a population-based cardiac surgery registry.

OBJECTIVE: To determine whether the probability of undergoing coronary bypass surgery within a certain time was related to the number of patients on the wait list at registration for the operation in a publicly funded health system. METHODS: A prospective cohort study comparing waiting times among patients registered on wait lists at the hospitals delivering adult cardiac surgery. For each calendar week, the list size, the number of new registrations, and the number of direct admissions immediately after angiography characterized the demand for surgery. RESULTS: The length of delay in undergoing treatment was associated with list size at registration, with shorter times for shorter lists (log-rank test 1,198.3, p<.0001). When the list size at registration required clearance time over 1 week patients had 42 percent lower odds of undergoing surgery compared with lists with clearance time less than 1 week (odds ratio [OR] 0.58 percent, 95 percent, confidence interval [CI] 0.53-0.63), after adjustment for age, sex, comorbidity, period, and hospital. The weekly number of new registrations exceeding weekly service capacity had an independent effect toward longer service delays when the list size at registration required clearance time less than 1 week (OR 0.56 percent, 95 percent CI 0.45-0.71), but not for longer lists. Every time the operation was performed for a patient requiring surgery without registration on wait lists, the odds of surgery for listed patients were reduced by 6 percent (OR 0.94, CI 0.93-0.95). CONCLUSION: For wait-listed patients, time to surgery depends on the list size at registration, the number of new registrations, as well as on the weekly number of patients who move immediately from angiography to coronary bypass surgery without being registered on a wait list. Hospital managers may use these findings to improve resource planning and to reduce uncertainty when providing advice on expected treatment delays.

Aged↗
PubMed2006

Unplanned emergency surgery in relation to length of wait lists at registration.

OBJECTIVE: To compare the cumulative incidence of emergency surgery between two groups of patients classified according to the length of wait lists at the time of their registration for coronary artery bypass grafting (CABG) and to test for significant differences in the risk of emergency surgery resulting from registration on a longer wait list. METHODS: A prospective study of all adult British Columbia residents who registered to undergo isolated CABG. We compared the time-dependent cumulative incidence for undergoing planned surgery through unplanned emergency admission before or during a certain wait-list week between two categories of wait-list size. The list size was a simple count of patients with higher or equal urgency to undergo CABG who were on a wait list at the time of registration of a new patient. RESULTS: Wait lists with one month or less of clearance time were observed in all urgent patients and were more prevalent in semi-urgent than non-urgent patients (79.1% vs 44.7%, respectively). The patients registered on a list with a clearance time of more than one month had a rate of unplanned emergency admission similar to those on a list with a clearance time of one month or less, OR = 1.07 (95% CI, 0.78-1.47) after adjustment for age, sex, comorbidity, calendar period, urgency and week on the list. During fifty-two weeks of the wait-list follow-up, an equal proportion of patients underwent unplanned emergency surgery after registration on lists in both clearance-time categories, OR = 1.03 (95% CI, 0.78-1.37) after adjustment. The number of patients who underwent CABG without having been registered on a wait list in the same hospital exerted no independent effect. CONCLUSIONS: The length of a wait list at registration had no effect on the probability that a semi-urgent or non-urgent patient would undergo CABG through unplanned emergency admission before or during a certain wait-list week.

Adult↗
PubMed2005

Classifying health-related quality of life outcomes of total hip arthroplasty.

BACKGROUND: Primary total hip arthroplasty (THA) is an effective treatment for hip osteoarthritis, assessed by whatever distribution-based measures of responsiveness. Yet, the group level evaluation has provided very little evidence contributes to our understanding of the large variation of treatment outcome. The objective is to develop criteria that classify individual treatment health related quality of life (HRQOL) outcome after primary THA, adjusted by preoperative scores. METHODS: We prospectively measured 147 patients' disease specific HRQOL on the date of consultation and 12 months post operation by Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Regression models were used to determine the "expected" outcome for a certain individual baseline score. The ceiling effect of WOMAC measurement is addressed by implementing a left-censoring method. RESULTS: The classification criteria are chosen to be the lower boundary of the 95% confidence interval (CI) of the estimated median from the regression. The robustness of the classification criteria was demonstrated using the Monte-Carlo simulation. CONCLUSION: The classification criteria are robust and can be applied in general orthopaedic research when the sample size is reasonable large (over 500).

Aged↗
PubMed2005

Policy analysis using patient flow simulations: conceptual framework and study design.

How do we know that innovations in healthcare delivery would work? In this paper, we discuss the idea of applying the methodology of group-randomized intervention studies to evaluation of surgical care policies using data from simulation experiments. We argue that a new interdisciplinary framework, which links health services research, operations research, and computer sciences, is required. Specifically, the methodological rigor of evaluative studies should be applied to the analysis of simulation experiments. In turn, the evaluation of policy initiatives should include the simulation of health-system operations. We introduce the framework and study design to evaluate methods for improving the peri-operative process with the use of patient flow simulations.

Adult↗
PubMed2004

Waiting time in relation to wait-list size at registration: statistical analysis of a waiting-list registry.

OBJECTIVE: To examine the relationship between the length of a waiting list for elective vascular surgery and the delay before undergoing the operation. METHODS: We undertook a prospective cohort study of patients registered on the waiting list for elective vascular surgery at an acute care hospital in Ontario. Regression analysis of wait times to express the admission rate in one group relative to another, with the ratio of rates being a measure of the difference between groups. RESULTS: List length at registration was associated with length of wait (log-rank test 596.4, p < 0.0001). Patients who were registered when the list length exceeded the weekly service capacity had 70% lower conditional probability of undergoing surgery than those on a list with fewer patients (rate ratio 0.30, 95% confidence interval [CI] 0.26-0.36) after adjustment for sex, age, procedure and period. Registering more than 5 patients when the list was short had an independent effect (rate ratio 0.61, CI 0.45-0.82). CONCLUSIONS: The number of registrants on a surgical wait list has an effect on the length of delay in providing necessary treatment. Our results suggest that a regulated list-length policy may contribute to reducing waiting times. Hospital managers may also use the findings to reduce uncertainty in reporting expected waits given the current list size, thereby improving resource planning.

Cohort Studies↗
PubMed2003

Risk of emergency admission while awaiting elective cholecystectomy.

BACKGROUND: There is uncertainty regarding the frequency of adverse events while on a surgical waiting list. We assess the relationship between the duration of wait for cholecystectomy and the risk of emergency admission. METHODS: We analyzed time to emergency admission in a group of 761 patients who underwent cholecystectomy after being seen in clinic for biliary colic and placed on waiting lists at 2 acute care centres in Ontario, from 1997 to 2000. RESULTS: Emergency admissions due to worsening symptoms occurred in 51 patients (6.7%) waiting for elective cholecystectomy. The weekly rate of emergency admission was low during the first 19 weeks on the list, but increased almost by a factor of 3 after 20 weeks (rate ratio 2.7; 95% confidence interval 2.0-3.7). Relative to the first 4 weeks on the list, the rate was 1.6 times higher after 20 weeks, 2 times higher after 28 weeks and 7 times higher after 40 weeks. INTERPRETATION: The probability that a patient on a waiting list will be admitted for emergency cholecystectomy consistently increases with the duration of wait, particularly after 20 weeks.

Adult↗
PubMed2003

Selective management of abdominal aortic aneurysms smaller than 5.0 cm in a prospective sizing program with gender-specific analysis.

PURPOSE: We present extended follow-up findings of the Kingston prospective sizing program for patients with abdominal aortic aneurysm (AAA) smaller than 5.0 cm in diameter, with gender-specific analysis. METHODS: From 1976 to 2001, 895 patients (688 men, 207 women) with AAA smaller than 5.0 cm were entered, regardless of fitness, in a prospective sizing program in which computed tomography scans were obtained every 6 months. Operations were performed in fit patients with an increase in AAA size to 5 cm (n = 190), AAA expansion greater than 0.5 cm in 6 months (n = 27), or for other reasons (n = 33). Follow-up continued until AAA rupture, surgery, death, or removal from the program. RESULTS: No AAA smaller than 5.0 cm ruptured during prospective follow-up. There was a statistically significant increase in expansion rate relative to size at entry, with the highest mean expansion rate of 0.52 cm/y for AAA 4.5 to 4.9 cm in diameter. There was no significant difference in AAA expansion rate between men and women. The frequency of surgery was inversely related to age at entry, but was positively related to AAA size at entry, with patients with AAA 4.5 to 4.9 cm at entry 6.8 times more likely (95% confidence interval, 4.3-10.7) to undergo surgery than those with AAA 3.0 to 3.4 cm at entry. Women were older than men at entry, and age at entry in those undergoing surgery was significantly greater in women. CONCLUSIONS: The study confirms the results of the United Kingdom Small Aneurysm Trial and the Aneurysm Detection and Management Study, that is, that risk for rupture is extremely unlikely with AAA smaller than 5.0 cm, which enables safe follow-up surveillance programs in both men and women with AAA smaller than 5.0 cm.

Aged↗
PubMed2003

The risk of rupture in untreated aneurysms: the impact of size, gender, and expansion rate.

OBJECTIVE: The purpose of this study was to establish the risk of rupture as related to size of abdominal aortic aneurysm (AAA), gender, and expansion of the aneurysm. METHODS: Between 1976 and 2001, 476 patients with conditions considered unfit for surgery with AAA 5.0 cm or more were followed with computed tomographic scans every 6 months until rupture, surgery, death, or deletion from follow-up. Surgery was performed for rupture (n = 22), improved medical condition (n = 37), increase in size (n = 95), symptoms (n = 17), and other reasons (n = 24). RESULTS: Fifty ruptures occurred during the follow-up period. The average risk of rupture (and standard error) in male patients with 5.0-cm to 5.9-cm AAA was 1.0% (0.01%) per year, in female patients with 5.0-cm to 5.9-cm AAA was 3.9% (0.15%) per year, in male patients with 6.0-cm or greater AAA was 14.1% (0.18%) per year, and in female patients with 6.0-cm or greater AAA was 22.3% (0.95%) per year. CONCLUSION: The risk of rupture in male patients with AAA 5.0 to 5.9 cm is low. The four-time higher risk of rupture in female patients with AAA 5.0 to 5.9 cm suggests a lower threshold for surgery be considered in fit women. The data regarding risk of rupture in patients with AAA 6.0 cm or more may allow more appropriate decision analysis for surgery in patients with unfit conditions with large AAA.

Aged↗