6 research outputs found
Propensity scores in the presence of effect modification: A case study using the comparison of mortality on hemodialysis versus peritoneal dialysis
Purpose. To control for confounding bias from non-random treatment assignment in observational data, both traditional multivariable models and more recently propensity score approaches have been applied. Our aim was to compare a propensity score-stratified model with a traditional multivariable-adjusted model, specifically in estimating survival of hemodialysis (HD) versus peritoneal dialysis (PD) patients. Methods. Using the Dutch End-Stage Renal Disease Registry, we constructed a propensity score, predicting PD assignment from age, gender, primary renal disease, center of dialysis, and year of first renal replacement therapy. We developed two Cox proportional hazards regression models to estimate survival on PD relative to HD, a propensity score-stratified model stratifying on the propensity score and a multivariable-adjusted model, and tested several interaction terms in both models. Results. The propensity score performed well: it showed a reasonable fit, had a good c-statistic, calibrated well and balanced the covariates. The main-effects multivariable-adjusted model and the propensity score-stratified univariable Cox model resulted in similar relative mortality risk estimates of PD compared with HD (0.99 and 0.97, respectively) with fewer significant covariates in the propensity model. After introducing the missing interaction variables for effect modification in both models, the mortality risk estimates for both main effects and interactions remained comparable, but the propensity score model had nearly as many covariates because of the additional interaction variables. Conclusion. Although the propensity score performed well, it did not alter the treatment effect in the outcome model and lost its advantage of parsimony in the presence of effect modification
Quality of life assessed with the medical outcomes study short form 36-item health survey of patients on renal replacement therapy: A systematic review and meta-analysis
Objectives: The Medical Outcomes Study Short Form
36-Item Health Survey (SF-36) is the most widely used
generic instrument to estimate quality of life of patients on
renal replacement therapy. Purpose of this study was to summarize
and compare the published literature on quality of life
of hemodialysis (HD), peritoneal dialysis (PD), and renal
transplant (RTx) patients.
Methods: We used random-effects regression analyses to
compare the SF-36 scores across treatment groups and
adjusted this comparison for age and prevalence of diabetes
using random-effects meta-regression analyses.
Results: We found 52 articles that met the inclusion criteria,
reporting quality of life of 36,582 patients. The unadjusted
scores of all SF-36 health dimensions were not significantly
different between HD and PD patients, but the scores of RTx
patients were higher than those of dialysis patients, except for
the dimensions Mental Health and Bodily Pain. Point differences
between dialysis and RTx patients varied from 2 to 32.
With adjustment for age and diabetes, the differences became
smaller (point difference 2–22). The significance of the differences
of both dialysis groups compared with RTx recipients
disappeared for the dimensions Vitality and Social
Functioning. The significance of the differences between HD
and RTx patients disappeared on the dimensions Physical
Functioning, Role Physical, and Bodily Pain.
Conclusion: We conclude that dialysis patients have a lower
quality of life than RTx patients, but this difference can
partly be explained by differences in age and prevalence of
diabetes.
Keywords: hemodialysis, meta-analysis, peritoneal dialysis,
quality of life, renal transplantation
Propensity scores in the presence of effect modification: A case study using the comparison of mortality on hemodialysis versus peritoneal dialysis
Abstract Purpose To control for confounding bias from non-random treatment assignment in observational data, both traditional multivariable models and more recently propensity score approaches have been applied. Our aim was to compare a propensity score-stratified model with a traditional multivariable-adjusted model, specifically in estimating survival of hemodialysis (HD) versus peritoneal dialysis (PD) patients. Methods Using the Dutch End-Stage Renal Disease Registry, we constructed a propensity score, predicting PD assignment from age, gender, primary renal disease, center of dialysis, and year of first renal replacement therapy. We developed two Cox proportional hazards regression models to estimate survival on PD relative to HD, a propensity score-stratified model stratifying on the propensity score and a multivariable-adjusted model, and tested several interaction terms in both models. Results The propensity score performed well: it showed a reasonable fit, had a good c-statistic, calibrated well and balanced the covariates. The main-effects multivariable-adjusted model and the propensity score-stratified univariable Cox model resulted in similar relative mortality risk estimates of PD compared with HD (0.99 and 0.97, respectively) with fewer significant covariates in the propensity model. After introducing the missing interaction variables for effect modification in both models, the mortality risk estimates for both main effects and interactions remained comparable, but the propensity score model had nearly as many covariates because of the additional interaction variables. Conclusion Although the propensity score performed well, it did not alter the treatment effect in the outcome model and lost its advantage of parsimony in the presence of effect modification.</p
Using heparin therapy to reverse protein-losing enteropathy in a patient with CDG-Ib
Background A 22-year-old female presented with edema, diarrhea, hypoalbuminemia and pancytopenia. She had previously been diagnosed with congenital disorder of glycosylation type Ib, and had a history of congenital hepatic fibrosis, portal hypertension and esophageal varices. In the past she had refused mannose therapy because of associated diarrhea and abdominal pain. Investigations Laboratory examinations, abdominal ultrasonography, bacterial and viral cultures of blood, urine and stools, double-balloon enteroscopy and fecal excretion test using Cr-51-labeled albumin. Diagnosis Protein-losing enteropathy. Management Infusion of albumin followed by intravenous and subcutaneous therapy with unfractionated heparin