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Groningen, Netherlands

Cranenburg E.C.M.,Maastricht University | Schurgers L.J.,Maastricht University | Uiterwijk H.H.,Dialysis Center Groningen | Beulens J.W.J.,University Utrecht | And 7 more authors.
Kidney International | Year: 2012

Vitamin K is essential for the activity of γ-carboxyglutamate (Gla)-proteins including matrix Gla28 protein and osteocalcin; an inhibitor of vascular calcification and a bone matrix protein, respectively. Insufficient vitamin K intake leads to the production of non-carboxylated, inactive proteins and this could contribute to the high risk of vascular calcification in hemodialysis patients. To help resolve this, we measured vitamin K1 and K2 intake (4-day food record), and the vitamin K status in 40 hemodialysis patients. The intake was low in these patients (median 140 μg/day), especially on days of dialysis and the weekend as compared to intakes reported in a reference population of healthy adults (mean K1 and K2 intake 200 μg/day and 31 μg/day, respectively). Non-carboxylated bone and coagulation proteins were found to be elevated in 33 hemodialysis patients, indicating subclinical hepatic vitamin K deficiency. Additionally, very high non-carboxylated matrix Gla28 protein levels, endemic to all patients, suggest vascular vitamin K deficiency. Thus, compared to healthy individuals, hemodialysis patients have a poor overall vitamin K status due to low intake. A randomized controlled trial is needed to test whether vitamin K supplementation reduces the risk of arterial calcification and mortality in hemodialysis patients. © 2012 International Society of Nephrology.


Hagedoorn M.,University of Groningen | Hein F.L.,University of Groningen | Schulz T.,University of Groningen | van der Heide J.J.H.,Academic Medical Center Amsterdam | And 4 more authors.
Health Psychology | Year: 2015

Background: Recruitment of participants for studies focusing on couples facing illness is a challenging task and participation decline may be associated with nonrandom factors creating bias. This study examines whether patient and relationship characteristics are associated with partner participation in research. Method: Patients invited to participate in a cross-sectional study on adaptation and quality of life after renal transplantation were asked to forward information about an add-on study to their partners. Results: A total of 456 participating patients had a partner; 293 of the partners showed interest in the study and 206 actually completed the questionnaire. Backward logistic regression analyses revealed that demographic, illness, and personal characteristics of the patient were not associated with partner interest in the study nor actual partner participation. However, partners who indicated interest in the study showed more active engagement toward the patients (as reported by the patients). Furthermore, patients of partners who actually completed the questionnaire reported less negative affect and higher relationship satisfaction than patients whose partner did not participate in the study. Discussion: It is encouraging that of the large number of variables tested, only 2 were associated with the participation of partners. Nevertheless, well-functioning couples appear to be overrepresented in our study, calling for specific effort to include marital distressed couples in research focusing on dyadic adaptation to illness. © 2014 American Psychological Association.


Schulz T.,University of Groningen | Niesing J.,University of Groningen | Homan Van Der Heide J.J.,University of Amsterdam | Westerhuis R.,Dialysis Center Groningen | And 2 more authors.
Transplantation Proceedings | Year: 2013

Although increased longevity of grafts has led to a growing number of long-term kidney transplant recipients, knowledge about the perceived health of these patients remains limited. A cross-sectional sample of 609 patients (60% response) was stratified into a short-term (≤1 year), midterm (>1 and ≤8 years), and long-term cohort (>8 and ≤15 years posttransplantation). Cohorts were compared for perceived health (Visual Analogue Scale of the EQ-5D), number of symptoms, and number of comorbidities by analysis of variance/covariance and multivariate regression analyses. Long-term patients reported more symptoms, (F[2, 606] = 3.09, P =.046) and more comorbidities, (F[2, 588] = 4.75, P =.009) but similar levels of perceived health, (F[2, 550] = 2.37, P >.05). Furthermore, symptoms were less influential for perceived health among long- versus short-term (z = -2.08, P =.038) or midterm cohorts (z = -2.60, P =.009). Previously identified predictors of perceived health accounted for less variance in the long-term as opposed to short-term (z = 4.30, P <.001) and midterm cohort (z = 2.07, P =.039). Despite more symptoms and comorbidities, the perceived health of long-term kidney transplant recipients was comparable to the short- and midterm, possibly due to selective survival or patient adjustment. Because kidney function and symptoms were predominantly associated with short-term perceived health, there is an urgent need to identify variables associated with long-term perceived health. © 2013 Elsevier Inc.


Kuipers J.,Dialysis Center Groningen | Usvyat L.A.,Renal Research Institute | Oosterhuis J.K.,University of Groningen | Dasselaar J.J.,University of Groningen | And 6 more authors.
American Journal of Kidney Diseases | Year: 2013

Background: Patients with thrice-weekly hemodialysis have higher predialysis weights and ultrafiltration rates at the first compared with subsequent dialysis sessions of the week. We hypothesized that these variations in weight and ultrafiltration rate are associated with a systematic difference in blood pressure. Study Design: Observational study. Setting & Participants: During 3 months, we prospectively collected hemodynamic data for 4,007 hemodialysis sessions involving 124 Dutch patients. A similar analysis was performed with 789 US patients, comprising 6,060 hemodialysis sessions. Factor: First versus subsequent hemodialysis sessions of the week. Outcomes: Blood pressure. Measurements: Blood pressure, weight, and ultrafiltration rate were analyzed separately for the first, second, and third dialysis sessions of the week. Comparisons were made with linear mixed models. Results: In Dutch patients, predialysis weight and ultrafiltration rate were significantly greater at the first compared with subsequent hemodialysis sessions of the week (P < 0.001). Predialysis systolic and diastolic blood pressures were higher at the first than at subsequent sessions of the week (P < 0.001). Predialysis blood pressure differences persisted throughout the session: systolic and diastolic blood pressures were on average 5.0 and 2.5 mm Hg higher during the first compared to the third session of the week. Postdialysis blood pressures followed a similar pattern (P < 0.001). Blood pressure differences between the first and subsequent days of the week persisted after adjustment for possible confounders. Results in the US cohort were materially identical despite differences in patient characteristics and treatment practice between the 2 cohorts. Limitations: Dry weight was not assessed by objective methods. Conclusions: Blood pressure of patients on a thrice-weekly dialysis schedule varies systematically over the week. Predialysis blood pressure is highest at the first hemodialysis session of the week, most likely due to greater interdialytic weight gain. Intra- and postdialytic blood pressures also are highest at the first session of the week despite higher ultrafiltration rates. © 2013 National Kidney Foundation, Inc.


Ipema K.J.R.,Dialysis Center Groningen | Ipema K.J.R.,Hanze University of Applied Sciences, Groningen | Van der Schans C.P.,Hanze University of Applied Sciences, Groningen | Vonk N.,University of Groningen | And 4 more authors.
Journal of Renal Nutrition | Year: 2012

Background: Malnutrition is an important cause of the excessive morbidity and mortality rate of dialysis patients. Frequent nocturnal home hemodialysis (NHHD) has many benefits compared with conventional thrice-weekly hemodialysis (CHD), due to the virtual absence of dietary restrictions and a much higher overall dialysis efficiency. In this observational study, we investigated whether these benefits of NHHD translate into an improved nutritional intake, with a special emphasis on protein intake. Methods: We prospectively assessed the effect of the transition of CHD to NHHD on nutritional intake (5-day dietary intake journal), normalized protein catabolic rate, and anthropometric parameters in 15 consecutive patients who started NHHD in our center between 2004 and 2009 and completed at least 8 months of follow-up. Data were collected before the transition from CHD to NHHD and 4 and 8 months after the transition. Results: Protein intake, as measured by both dietary intake journal and normalized protein catabolic rate, increased significantly after the transition from CHD to NHHD. Accordingly, phosphate intake increased significantly; however, serum phosphate levels did not increase, despite negligible phosphate binder use during NHHD. Body mass index and upper arm muscle circumference did not change significantly. Conclusion: The transition from CHD to NHHD has a positive effect on nutritional intake, in particular, protein intake. NHHD should be considered in malnourished patients on CHD. © 2012 National Kidney Foundation, Inc.

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