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Biomedical subjects

John P A Puvimanasinghe

Publications and source records attributed to John P A Puvimanasinghe.

7 recordsLinked to original sources
PubMed2006

Comparison of Carpentier-Edwards pericardial and supraannular bioprostheses in aortic valve replacement.

OBJECTIVE: This study aimed at calculating and comparing the long-term outcomes of patients after aortic valve replacement with the Carpentier-Edwards bovine pericardial and porcine supraannular bioprostheses using microsimulation. METHODS: We conducted a meta-analysis of eight studies on the Carpentier-Edwards pericardial valves (2,685 patients, 12,250 patient-years) and five studies on the supraannular valves (3,796 patients, 20,127 patient-years) to estimate the occurrence rates of valve-related events. Eighteen-year follow-up data sets were used to construct age-dependent Weibull curves that described their structural valvular deterioration. The estimates were entered into a microsimulation model, which was used to calculate the outcomes of patients after aortic valve replacement. RESULTS: The annual hazard rates for thrombo-embolism after aortic valve replacement were 1.35% and 1.76% for the pericardial and supraannular valves, respectively. For a 65-year-old male, median time to structural valvular deterioration was 20.1 and 22.2 years while the lifetime risk of reoperation due to structural valvular deterioration was 18.3% and 14.0%, respectively. The life expectancy of the patient was 10.8 and 10.9 years and event-free life expectancy 9.0 and 8.8 years, respectively. CONCLUSIONS: The microsimulation methodology provides insight into the prognosis of a patient after aortic valve replacement with any given valve type. Both the Carpentier-Edwards pericardial and supraannular valve types perform satisfactorily, especially in elderly patients, and show no appreciable difference in long-term outcomes when implanted in the aortic position.

Aged↗
PubMed2006

Long-term survival after non-small cell lung cancer surgery: development and validation of a prognostic model with a preoperative and postoperative mode.

OBJECTIVE: At present, there is no prognostic model that is specific for prediction of survival after non-small cell lung cancer surgery. We aimed to develop a prognostic model that can be used to estimate the postoperative survival of individual patients. METHODS: A total of 766 patients underwent resection for primary non-small cell lung cancer. Comorbid conditions were scaled according to the Charlson comorbidity index (CCI). Cox proportional hazard analyses were used to determine risk factors for survival. A prognostic model for survival with a preoperative and postoperative mode was established. Performance of the prognostic model, the CCI, and pathologic tumor stage were quantified by a concordance statistic to indicate discriminative ability. RESULTS: The factors associated with an impaired survival were male sex, age, chronic obstructive pulmonary disease, congestive heart failure, any prior tumor, moderate-to-severe renal disease (preoperative and postoperative mode), clinical tumor stage (preoperative mode), type of resection, and pathologic tumor stage (postoperative mode). The discriminative performance was poor for the CCI (c = 0.55), better for pathologic tumor stage (c = 0.60) and for the preoperative mode (c = 0.61), and best for the postoperative mode (c = 0.65). The discriminative performance of the postoperative mode was better than the discriminative performance of the CCI (P < .0001), the preoperative mode (P < .0002), and pathologic tumor stage (P < .0001). The discriminative performance of the preoperative mode was better than the discriminative performance of the CCI (P < .0001) and similar (P = .90) to a model that only included pathologic tumor stage. CONCLUSIONS: The prognostic model, particularly the postoperative mode, successfully estimates long-term survival of individual patients and could help clinicians in clinical decision-making and treatment tailoring.

Aged↗
PubMed2005

Prognosis after aortic valve replacement with the Carpentier-Edwards pericardial valve: use of microsimulation.

BACKGROUND: The second-generation Carpentier-Edwards pericardial valve (Edwards Lifesciences LLC, Irvine, CA) is widely used for aortic valve replacement. However, knowledge on the long-term outcomes of patients after valve implantation is incomplete. We used microsimulation to calculate the long-term outcome of any given patient after aortic valve replacement with the Carpentier-Edwards pericardial valve. METHODS: A meta-analysis of 8 reports on aortic valve replacement with the Carpentier-Edwards pericardial valve (2,685 patients; 12,250 patient years) was used to estimate the hazards of valve-related events other than structural valvular deterioration. Structural valvular deterioration was described by age-dependent Weibull curves calculated from 18-year follow-up, premarket approval, Carpentier-Edwards pericardial primary data. These estimates provided the input data for the parameters of the microsimulation model, which was then used to calculate the outcomes of patients of different ages after valve implantation. The model estimates of survival were validated using two external data sets. RESULTS: The Weibull analysis estimated a median time to reoperation for structural valvular deterioration ranging from 18.1 years for a 55-year-old male to 23.2 years for a 75-year-old male. For a 65-year-old male, microsimulation calculated a life expectancy and event-free life expectancy of 10.8 and 9.1 years, respectively. The lifetime risk of at least one valve-related event was 38% and that of reoperation due to structural valvular deterioration 17%, respectively, for this patient. The model estimates of survival showed good agreement with external data. CONCLUSIONS: Microsimulation provides detailed insight into the long-term prognosis of patients after aortic valve replacement. The Carpentier-Edwards pericardial valve performs satisfactorily and offers a low lifetime risk of reoperation due to structural valvular deterioration, especially for elderly patients requiring aortic valve replacement.

Adult↗
PubMed2003

Measles outbreak in Sri Lanka, 1999-2000.

A large measles outbreak occurred in Sri Lanka from October 1999 through June 2000 following a period of low incidence. During this period, >15,000 suspected cases were reported to the central Epidemiological Unit of the Department of Health Services. The outbreak was investigated through review of surveillance data for 1999-2000, which were compared with previous surveillance data. Among the clinically confirmed cases, the highest morbidity rate (114/100,000 population) was observed among children <9 months of age. Nearly 54% of the cases were among persons >/=15 years old, and this percentage had increased over the previous decade. Forty percent of cases had a history of measles vaccination. There were 5 deaths, giving a case-fatality rate of 0.1%. Action taken during the outbreak and plans for future outbreak prevention strategies were also evaluated.

Adolescent↗
PubMed2003

Choice of a mechanical valve or a bioprosthesis for AVR: does CABG matter?

OBJECTIVE: Mechanical valves and bioprostheses are the commonly used devices in aortic valve replacement (AVR). Many patients with valvular disease also require concomitant coronary artery bypass grafting (CABG). We used a microsimulation model to provide insight into the outcomes of patients after AVR with mechanical valves and stented bioprostheses, with and without CABG, and to determine the age-thresholds or age crossover points in outcomes between the two valve types. METHODS: We conducted a meta-analysis of published results after primary AVR with mechanical prostheses (nine reports, 4274 patients, 25,726 patient-years) and stented porcine bioprostheses (13 reports, 9007 patients, 54,151 patient-years) to estimate risks of valve-related events. A hazard ratio of 1.3 was used to incorporate the effect of CABG on long-term survival. Estimates were entered into a microsimulation model, which was then used to predict the outcomes of patients after AVR, with and without CABG. The model calculations were validated using a large data set from Portland, USA. RESULTS: For a 65-year-old male without CABG, the life expectancy (LE) was 11.2 and 11.6 years and the event-free life expectancy (EFLE) was 8.2 and 8.9 years, respectively, after implantation with mechanical valves and bioprostheses. The lifetime risk of at least one valve-related event was 51 and 47%, respectively. The age crossover point between the two valve types, considering the above outcome parameters, was 59, 60 and 63 years, respectively. CABG reduced LE and consequently EFLE and lifetime risk of an event, but only minimally influenced the patient age crossover points. The model calculations showed good agreement with the Portland data. CONCLUSIONS: The currently recommended patient age for using a bioprosthesis (65 years) could be lowered further, irrespective of concomitant CABG. The trade-off between the reduced risks of bioprosthetic failure and of hemorrhage in mechanical valves, resulting from a lower LE, minimized the effect of CABG on the age crossover points between the two valve types.

Adolescent↗