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Dive into the research topics where Tor-Ivar Karlsen is active.

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Featured researches published by Tor-Ivar Karlsen.


European Journal of Endocrinology | 2010

Obesity-related cardiovascular risk factors after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention

Dag Hofsø; Njord Nordstrand; Line Kristin Johnson; Tor-Ivar Karlsen; Helle Hager; Trond Jenssen; Jens Bollerslev; Kristin Godang; Rune Sandbu; Jo Røislien; Jøran Hjelmesæth

Objective Weight reduction improves several obesity-related health conditions. We aimed to compare the effect of bariatric surgery and comprehensive lifestyle intervention on type 2 diabetes and obesity-related cardiovascular risk factors. Design One-year controlled clinical trial (ClinicalTrials.gov identifier NCT00273104). Methods Morbidly obese subjects (19–66 years, mean (s.d.) body mass index 45.1 kg/m2 (5.6), 103 women) were treated with either Roux-en-Y gastric bypass surgery (n=80) or intensive lifestyle intervention at a rehabilitation centre (n=66). The dropout rate within both groups was 5%. Results Among the 76 completers in the surgery group and the 63 completers in the lifestyle group, mean (s.d.) 1-year weight loss was 30% (8) and 8% (9) respectively. Beneficial effects on glucose metabolism, blood pressure, lipids and low-grade inflammation were observed in both groups. Remission rates of type 2 diabetes and hypertension were significantly higher in the surgery group than the lifestyle intervention group; 70 vs 33%, P=0.027, and 49 vs 23%, P=0.016. The improvements in glycaemic control and blood pressure were mediated by weight reduction. The surgery group experienced a significantly greater reduction in the prevalence of metabolic syndrome, albuminuria and electrocardiographic left ventricular hypertrophy than the lifestyle group. Gastrointestinal symptoms and symptomatic postprandial hypoglycaemia developed more frequently after gastric bypass surgery than after lifestyle intervention. There were no deaths. Conclusions Type 2 diabetes and obesity-related cardiovascular risk factors were improved after both treatment strategies. However, the improvements were greatest in those patients treated with gastric bypass surgery.


Surgery for Obesity and Related Diseases | 2015

Health-related quality of life after bariatric surgery: a systematic review of prospective long-term studies

John Roger Andersen; Anny Aasprang; Tor-Ivar Karlsen; Gerd Karin Natvig; Villy Våge; Ronette L. Kolotkin

Impaired health-related quality of life (HRQoL) is common in bariatric surgery candidates and is often one of the motivating factors for seeking bariatric surgery. Although many studies have reported changes in HRQoL after bariatric surgery, few are long-term prospective studies and no systematic review has been conducted. A systematic database search identified studies reporting HRQoL preoperatively and≥5 years after bariatric surgery. Change in HRQoL over time was the outcome variable, divided into primary and secondary outcomes. Seven prospective cohort studies met the inclusion criteria. Eight HRQoL measures and 6 surgical methods were identified. Long-term follow-up time ranged from 5-10 years, sample sizes from 44 to 655 patients, and follow-up rates from 61% to 92%. None of the 7 studies were randomized controlled trials, and only 2 studies used control groups. Six of 7 studies showed statistically significant improvements in all of the primary outcomes, and 1 study showed statistically significant improvements in 1 of 2 primary outcomes. Of the statistically significant HRQoL improvements, 92% were clinically meaningful. Peak improvements in primary HRQoL outcomes were typically observed during the first years of follow-up, followed by a gradual decline that seemed to stabilize 5 years postoperatively. Long-term HRQoL scores typically remained improved relative to preoperative scores but were somewhat below population norm scores. In conclusion, while bariatric surgery candidates reported impaired HRQoL presurgically, their HRQoL improved considerably after bariatric surgery and much of the initial HRQoL improvements were maintained over the long term.


Health and Quality of Life Outcomes | 2013

Health related quality of life after gastric bypass or intensive lifestyle intervention: a controlled clinical study

Tor-Ivar Karlsen; Randi Størdal Lund; Jo Røislien; Serena Tonstad; Gerd Karin Natvig; Rune Sandbu; Jøran Hjelmesæth

BackgroundThere is little robust evidence relating to changes in health related quality of life (HRQL) in morbidly obese patients following a multidisciplinary non-surgical weight loss program or laparoscopic Roux-en-Y Gastric Bypass (RYGB). The aim of the present study was to describe and compare changes in five dimensions of HRQL in morbidly obese subjects. In addition, we wanted to assess the clinical relevance of the changes in HRQL between and within these two groups after one year. We hypothesized that RYGB would be associated with larger improvements in HRQL than a part residential intensive lifestyle-intervention program (ILI) with morbidly obese subjects.MethodsA total of 139 morbidly obese patients chose treatment with RYGB (n=76) or ILI (n=63). The ILI comprised four stays (seven weeks) at a specialized rehabilitation center over one year. The daily schedule was divided between physical activity, psychosocially-oriented interventions, and motivational approaches. No special diet or weight-loss drugs were prescribed. The participants completed three HRQL-questionnaires before treatment and 1 year thereafter. Both linear regression and ANCOVA were used to analyze differences between weight loss and treatment for five dimensions of HRQL (physical, mental, emotional, symptoms and symptom distress) controlling for baseline HRQL, age, age of onset of obesity, BMI, and physical activity. Clinical relevance was assessed by effect size (ES) where ES<.49 was considered small, between .50-.79 as moderate, and ES>.80 as large.ResultsThe adjusted between group mean difference (95% CI) was 8.6 (4.6,12.6) points (ES=.83) for the physical dimension, 5.4 (1.5–9.3) points (ES=.50) for the mental dimension, 25.2 (15.0–35.4) points (ES=1.06) for the emotional dimension, 8.7 (1.8–15.4) points (ES=.37) for the measured symptom distress, and 2.5 for (.6,4.5) fewer symptoms (ES=.56), all in favor of RYGB. Within-group changes in HRQOL in the RYGB group were large for all dimensions of HRQL. Within the ILI group, changes in the emotional dimension, symptom reduction and symptom distress were moderate. Linear regression analyses of weight loss on HRQL change showed a standardized beta-coefficient of –.430 (p<.001) on the physical dimension, –.288 (p=.004) on the mental dimension, –.432 (p<.001) on the emotional dimension, .287 (p=.008) on number of symptoms, and .274 (p=.009) on reduction of symptom pressure.ConclusionsMorbidly obese participants undergoing RYGB and ILI had improved HRQL after 1 year. The weaker response of ILI on HRQL, compared to RYGB, may be explained by the difference in weight loss following the two treatments.Trial registrationClinical Trials.gov number NCT00273104


Obesity Facts | 2011

Validity of the SF-36 in Patients with Morbid Obesity

Tor-Ivar Karlsen; Einar K. Tveitå; Gerd Karin Natvig; Serena Tonstad; Jøran Hjelmesæth

Background: The Medical Outcome Study 36-Item Short Form Health Survey (SF-36) is one of the most commonly applied generic quality of life instruments. The construct validity of the instrument in patients with morbid obesity is not established. Participants and Methods: A total of 475 morbidly obese patients (68% women) with a mean (standard deviation) age of 44.7 (11.8) years, weight of 123.5 (24.1) kg and BMI of 41.7 (6.3) kg/m2, who had been referred to a rehabilitation center, completed the SF-36 form. Exploratory factor analyses were performed to examine the underlying component structure of the questionnaire. Confirmatory factor analyses were performed to assess model fit. Results: The analysis suggested a 6-component structure rather than the 8-component structure used in the original SF-36. The first component consisted of items from the physical functioning subscale, the role physical subscale and the general health subscale, and explained 31% of the variance. The 6 components explained 61% of the total variance. The items loaded as expected in a physical and mental component. The assessment of model fit confirmed these findings. Conclusion: The 2 summary scales of the SF-36 have satisfactory validity in patients with morbid obesity. However, the validity of the 8 subscales is questionable, and the subscales should be interpreted with care.


Obesity Surgery | 2011

Employment Is Associated with the Health-Related Quality of Life of Morbidly Obese Persons

Randi Størdal Lund; Tor-Ivar Karlsen; Dag Hofsø; Jan Magnus Fredheim; Jo Røislien; Rune Sandbu; Jøran Hjelmesæth

BackgroundWe aimed to investigate whether employment status was associated with health-related quality of life (HRQoL) in a population of morbidly obese subjects.MethodsA total of 143 treatment-seeking morbidly obese patients completed the Medical Outcome Study 36-Item Short-Form Health Survey (SF-36) and the Obesity and Weight-Loss Quality of Life (OWLQOL) questionnaires. The former (SF-36) is a generic measure of physical and mental health status and the latter (OWLQOL) an obesity-specific measure of emotional status. Multiple linear regression analyses included various measures of the HRQoL as dependent variables and employment status, education, marital status, gender, age, body mass index (BMI), type 2 diabetes, hypertension, obstructive sleep apnea, and treatment choice as independent variables.ResultsThe patients (74% women, 56% employed) had a mean (SD, range) age of 44 (11, 19–66) years and a mean BMI of 44.3 (5.4) kg/m2. The employed patients reported significantly higher HRQoL scores within all eight subscales of SF-36, while the OWLQOL scores were comparable between the two groups. Multiple linear regression confirmed that employment was a strong independent predictor of HRQoL according to the SF-36. Based on part correlation coefficients, employment explained 16% of the variation in the physical and 9% in the mental component summaries of SF-36, while gender explained 22% of the variation in the OWLQOL scores.ConclusionEmployment is associated with the physical and mental HRQoL of morbidly obese subjects, but is not associated with the emotional aspects of quality of life.


Health and Quality of Life Outcomes | 2013

Predictors of weight loss after an intensive lifestyle intervention program in obese patients: a 1-year prospective cohort study.

Tor-Ivar Karlsen; Maryon Søhagen; Jøran Hjelmesæth

BackgroundStudies of lifestyle intervention programs in morbid obesity report large variations in weight loss outcomes. This is reported not only between but also within standardized programs. Such reports point to participants’ characteristics as possible predictors of this outcome. The aim of this prospective cohort study was to identify predictors of weight loss after a 1-year partly residential intensive lifestyle intervention program (ILI).MethodsMorbidly obese patients (n=199), all Caucasian, 71% women, mean (SD) age 45.2 (11.1) years, body mass index (BMI) 42.0 (6.2) kg/m2, and excess body weight (>BMI=25 kg/m2) 49.4 (19.6) kg, were referred from public hospitals to a rehabilitation center and enrolled consecutively. The 1-year ILI comprised of four (n=104) or five (n=95) stays at the rehabilitation center. In both cases there was one main stay for 4 weeks and the remaining stays lasted 1 week each. In the home periods the patients were followed up by telephone and by their general practitioners (GP). The patients were also encouraged to use a predefined paper based diary. Health related quality of life (HRQL), diagnostic, anthropometric, socio-demographic, psychosocial and intervention characteristics were measured at baseline, 12 weeks and 1 year. Multiple linear regression analyses were performed to extract possible predictors of weight loss at 1-year. Direct and indirect effects of these predictors were tested through structural equation modeling.ResultsThe mean (SD) 1-year weight loss was 10 (11) kg, corresponding to an 8 (8) % reduction of body weight from baseline. Mean excess weight loss (EWL) was 20 (22) % ranging from 104% to -77%. The adherence to a diary (r=.16), type 2 diabetes (r=-.14) and frequency of GP-visits (r=.23) were significantly associated with EWL at 12 weeks. Predictors of 1-year EWL were 12 week EWL (r=.66), occupational status (r=.11), age (r=.19), and mental HRQL (r=-.16), all p<.05. The path model explained 50% of the variation (r2=.50) of 1-year EWL.ConclusionLarger 12 week weight loss, being employed, lower mental HRQL and being older predicts larger weight loss after 1 year in morbidly obese patients following ILI. Not having type 2 diabetes, using a diary combined with regular GP follow-up influence the 12-week weight loss.Trial registrationClinicaltrials.gov: NCT00477399


JAMA Surgery | 2016

Standard vs Distal Roux-en-Y Gastric Bypass in Patients With Body Mass Index 50 to 60: A Double-blind, Randomized Clinical Trial

Hilde Risstad; Marius Svanevik; Jon Kristinsson; Jøran Hjelmesæth; Erlend T. Aasheim; Dag Hofsø; Torgeir T. Søvik; Tor-Ivar Karlsen; Morten W. Fagerland; Rune Sandbu; Tom Mala

Importance Up to one-third of patients undergoing bariatric surgery have a body mass index (BMI) of more than 50. Following standard gastric bypass, many of these patients still have a BMI greater than 40 after peak weight loss. Objective To assess the efficacy and safety of standard gastric bypass vs distal gastric bypass in patients with a BMI of 50 to 60. Design, Setting, and Participants Double-blind, randomized clinical parallel-group trial at 2 tertiary care centers in Norway (Oslo University Hospital and Vestfold Hospital Trust) between May 2011 and April 2013. The study included 113 patients with a BMI of 50 to 60 aged 20 to 60 years. The 2-year follow-up was completed in May 2015. Interventions Standard gastric bypass (alimentary limb, 150 cm) and distal gastric bypass (common channel, 150 cm), both with a biliopancreatic limb of 50 cm and a gastric pouch of about 25 mL. Main Outcomes and Measures Primary outcome was the change in BMI from baseline until 2 years after surgery. Secondary outcomes were cardiometabolic risk factors, nutritional outcomes, adverse events, gastrointestinal symptoms, and health-related quality of life. Results At baseline, the mean age of the patients was 40 years (95% CI, 38-41 years), 65% were women, mean BMI was 53.5 (95% CI, 52.9-54.0), and mean weight was 158.8 kg (95% CI, 155.3-162.3 kg). The mean reduction in BMI was 17.8 (95% CI, 16.9-18.6) after standard gastric bypass and 17.2 (95% CI, 16.3-18.0) after distal gastric bypass, and the mean between-group difference was 0.6 (95% CI, -0.6 to 1.8; P = .32). Reductions in mean levels of total and low-density lipoprotein cholesterol were greater after distal gastric bypass than standard gastric bypass, and between-group differences were 19 mg/dL (95% CI, 11-27 mg/dL ) and 28 mg/dL (95% CI, 21 to 34 mg/dL), respectively (P < .001 for both). Reductions in fasting glucose levels and hemoglobin A1c were greater after distal gastric bypass. Secondary hyperparathyroidism and loose stools were more frequent after distal gastric bypass. The number of adverse events and changes in health-related quality of life did not differ between the groups. Importantly, 1 patient developed liver failure and 2 patients developed protein-caloric malnutrition treated by elongation of the common channel following distal gastric bypass. Conclusions and Relevance Distal gastric bypass was not associated with a greater BMI reduction than standard gastric bypass 2 years after surgery. However, we observed different changes in cardiometabolic risk factors and nutritional markers between the groups. Trial Registration Clinicaltrials.gov Identifier: NCT00821197.


Archive | 2014

Obesity and Its Impact Upon Quality of Life

John Roger Andersen; Tor-Ivar Karlsen; Ronette L. Kolotkin

Obesity may have a negative effect on quality of life (QOL) and is an important outcome in the treatment of obesity. In this chapter we discuss the concept of QOL; the measurement of QOL; the mechanisms by which obesity may influence the physical, social, mental, and sexual aspects of QOL; and the effects of weight loss interventions on QOL. Finally, we discuss how health professionals may use QOL measures to improve the quality of clinical practice.


Clinical obesity | 2013

The effectiveness of secondary and tertiary care lifestyle intervention in morbidly obese patients: a 1-year non-randomized controlled pragmatic clinical trial

E Gjevestad; Tor-Ivar Karlsen; Jo Røislien; S. Mæhlum; Jøran Hjelmesæth

In this non‐randomized clinical pragmatic trial, we aimed to compare the effectiveness of an outpatient intensive lifestyle intervention (ILI) programme conducted in a tertiary care obesity rehabilitation centre with an outpatient moderate lifestyle intervention (MLI) programme at a secondary care obesity centre. Effectiveness was measured in terms of the 1‐year effect each programme had on body weight, physical activity and health‐related quality of life (HRQL). A total of 232 morbidly obese subjects were recruited to the ILI group and 140 to the MLI group, with retention rates of 78% and 44%, respectively. The ILI group had a significantly larger mean (95% confidence interval [CI]) weight loss than the MLI group, 11% (9%, 12%) vs. 2% (1%, 6%), P < 0.001, and a larger proportion of completers attaining ≥5% weight loss (71% vs. 33%), P < 0.001. Compared with the MLI group, the ILI group achieved a significant larger mean (95% CI) increase in the physical dimension of HRQL 6.9 (4.4, 9.3), P < 0.001, the mental dimension of HRQL 4.4 (1.4, 7.4), P = 0.018 and in the emotional dimension of HRQL 17.8 (12.8, 22.6), P < 0.001. There were no significant differences in terms of changes in physical activity. Compared with MLI, ILI was associated with significantly larger weight loss and better HRQL.


Local Government Studies | 2018

Drivers and barriers of inter-municipal cooperation in health services – the Norwegian case

Bjørnulf Arntsen; Dag Olaf Torjesen; Tor-Ivar Karlsen

ABSTRACT Inter-municipal cooperation in service delivery is widespread, as is the notion that this type of cooperation is primarily driven by economies of scale. However, the empirical results appear to be inconclusive, suggesting that additional explanatory factors are needed to explain why municipalities cooperate. This study aimed to identify the factors and conditions that influence the level of inter-municipal cooperation in health services by exploring a broad set of explanatory factors that go beyond simple economic concerns. In addition to confirming that a small population-size and fiscal stress constitute important drivers of inter-municipal cooperation, the results from this study also demonstrates the need to consider geographical location and heterogeneity relative to neighbouring municipalities as potential barriers to such cooperation.

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Dag Hofsø

Oslo University Hospital

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Jo Røislien

University of Stavanger

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Hilde Risstad

Oslo University Hospital

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Tom Mala

Oslo University Hospital

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