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To establish whether there is more psychological distress among recipients of Björk-Shiley convex... more To establish whether there is more psychological distress among recipients of Björk-Shiley convexo-concave (BScc) valves than among recipients of other valves not known to fracture. Cross sectional study. 137 patients who received either a BScc valve or a Sorin Biomedical spherical valve during a randomised trial between 1982 and 1983 at St Antonius Hospital, Nieuwegein. Systematic notification of the risk of strut fracture in recipients of BScc valves was carried out at St Antonius Hospital in 1991. Psychological distress as assessed with the General Severity Index from the Symptom Checklist 90. Psychological distress between recipients of BScc and Sorin valves did not differ irrespective of whether the recipients knew their valve type. More recipients of BScc valves, however, knew their valve type and of problems associated with artificial heart valves. Information about an increased risk of strut fracture does not induce psychological distress among well informed recipients of BScc valves. All recipients of heart valves should be systematically informed about their valve type--for example, by issuing data cards with valve serial numbers and other relevant information.

$Research paper thumbnail of Which manufacturing characteristics are predictors of outlet strut fracture in large sixty-degree Björk-Shiley convexo-concave mitral valves$

Journal of Thoracic and Cardiovascular Surgery, 1999

Identification of predictors of outlet strut fracture is important for recipients of large (&... more Identification of predictors of outlet strut fracture is important for recipients of large (>/=29 mm) 60-degree Björk-Shiley convexo-concave mitral valves when it comes to decision making on prophylactic explantation. An association between the manufacturing process of Björk-Shiley convexo-concave valves and the risk of fracture has been suggested. The aim of this study was to determine which items from the manufacturing records, in addition to known risk factors, were predictive of fracture of large 60-degree Björk-Shiley convexo-concave mitral valves. All Dutch recipients (n = 2264) of Björk-Shiley convexo-concave valves were followed up until fracture, death, reoperation, or end of the study (July 1, 1996). Information was abstracted from the manufacturing records of large 60-degree Björk-Shiley convexo- concave mitral valves (n = 655) in Dutch recipients and included items that described the manufacturing process and items for which an association with strut fracture had been suggested. Manufacturing records were available for 637 valves (97%), including 25 fractured valves. Multivariate analysis identified age at implantation (hazard ratio 0.95, 95% confidence interval 0.93-0.97), lot size (<175 valves versus >/=175 valves; hazard ratio 6.6, 95% confidence interval 2.2-20.1), number of hook deflection tests performed (0 or 1 versus >/=2; hazard ratio 4.7, 95% confidence interval 1.4-16.2), number of disks that were used (1 versus >/=2; hazard ratio 5.9, 95% confidence interval 1.9-18.5), and lot fracture percentage (hazard ratio 1.6, 95% confidence interval 1.4-1. 8) as independent predictors of fracture. Although the added predictive value of a model with these 5 variables was sizable compared with a model containing age only, it was only slightly better than a model with age, lot size, and lot fracture percentage. If the serial number of a large 60-degree Björk-Shiley convexo-concave mitral valve is known, manufacturing information can add significantly to the prediction of fracture. Information on lot size and lot fracture percentage should be made available to clinicians for risk assessment of prophylactic explantation.

Journal of Clinical Epidemiology, 2003

American Journal of Cardiology, 2000

Journal of Thoracic and Cardiovascular Surgery, 1998

$Research paper thumbnail of Likelihood of underreporting of outlet strut fracture from examination of the Dutch Björk-Shiley CC cohort$

American Journal of Cardiology, 1998

The Dutch Björk-Shiley convexo-concave (BScc) cohort serves as a reference population on the risk... more The Dutch Björk-Shiley convexo-concave (BScc) cohort serves as a reference population on the risk of outlet strut fracture and is being used to formulate guidelines for prophylactic replacement. Fractures, however, may be undetected at death. The aim of this study was to quantify the degree of underestimation of strut fracture in the Dutch BScc cohort. Multivariate Cox regression analysis was used to assess the relative and absolute risk of death from different causes within 14 years. The unexplained "excess" mortality among 70 degrees BScc valve recipients was attributed to unreported fatal strut fractures and used to estimate its extent in this group, which then was extrapolated to the 60 degrees BScc valve recipients. For 70 degrees BScc valve recipients, the adjusted hazard ratio for death from all causes except strut fracture was 1.2 (95% confidence interval [CI] 1.0 to 1.5). The 14-year absolute risks for 70 degrees and 60 degrees BScc valve recipients were 44% and 37%, respectively. Among 70 degrees and 60 degrees BScc valve recipients, underreporting of fracture was estimated to be 25% (95% CI 0 to 49) and 26% (95% CI 0 to 52), respectively. Estimates based on sudden death and fatal congestive heart failure yielded essentially the same results. Thus, underreporting of fatal strut fracture in the Dutch BScc cohort is estimated to be approximately 25%. Hence, the risk and lethality of fracture of BScc valves are underestimated and indications for prophylactic replacement should be adjusted accordingly. For example, the advantage of valve replacement in a 40-year-old patient with a 29-mm 60 micro BScc mitral valve would almost double to 0.82 years.

$Research paper thumbnail of Welder identity, weld date, and the risk of outlet strut fracture in Björk-Shiley convexo-concave valves: the Dutch cohort study$

Medical Decision Making, 2000

Björk-Shiley convexo-concave (BScc) mechanical heart valves have a risk of outlet strut fracture.... more Björk-Shiley convexo-concave (BScc) mechanical heart valves have a risk of outlet strut fracture. Decision-analytic models may support decision making regarding prophylactic replacement to avert the disastrous consequences of fracture. Assumptions and estimates from previous analyses were evaluated to develop an accurate new decision model, incorporating updated follow-up experience from 2,263 patients with BScc valves implanted between 1979 and 1985 in The Netherlands. The authors focus on estimation of fracture risks (50 events) and survival (883 deaths, excluding fractures). In previous analyses, fracture risk was estimated with widely varying combinations of patient, valve, and production characteristics. Two analyses assumed a constant fracture hazard during follow-up, while data from the present study suggest that risk decreases with increasing age during follow-up. An additive excess-risk model was applied in two analyses to estimate survival. The assumption of a constant additive excess risk was not supported by the Dutch data, which suggest that the life expectancies of patients currently alive with BScc valves may be shorter than previously believed. Based on the revised decision model, over 90% of the currently alive Dutch BScc valve patients do not benefit from replacement, since the fracture risk causes only a minor reduction of remaining life expectancy. The variation in essential assumptions of previous decision analyses directly affected the indication for prophylactic replacement. This study shows how detailed statistical analyses may guide modeling choices in a decision analysis.

Tsg, 2007

Prestatiemeting in de gezondheidszorg en met name rond klinische zorg wint toenemend aan belang e... more Prestatiemeting in de gezondheidszorg en met name rond klinische zorg wint toenemend aan belang en de verwachtingen zijn hooggespannen. Met name bij anderen dan de beroepsbeoefenaren zelf leeft de hoop dat met het gebruik van prestatie-indicatoren zorg inzichtelijker wordt. De vraag naar transparantie vanuit de overheid, de zorgverzekeraars, en de zorggebruikers illustreert dat zorgaanbieders er niet meer vanuit kunnen gaan dat externe partijen de kwaliteit van de zorg vanzelfsprekend vinden.