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Featured researches published by P. Christensen.


Annals of the Rheumatic Diseases | 2013

EULAR recommendations for the non-pharmacological core management of hip and knee osteoarthritis

Linda Fernandes; Kåre Birger Hagen; Johannes W. J. Bijlsma; Øyvor Andreassen; P. Christensen; Philip G. Conaghan; Michael Doherty; Rinie Geenen; Alison Hammond; Ingvild Kjeken; L. Stefan Lohmander; Hans Lund; Christian D. Mallen; Tiziana Nava; Susan Oliver; Karel Pavelka; Irene A Pitsillidou; José António Pereira da Silva; Jenny de la Torre; Gustavo Zanoli; Theodora P. M. Vliet Vlieland

The objective was to develop evidence -based recommendations and a research and educational agenda for the non-pharmacological management of hip and knee osteoarthritis (OA). The multidisciplinary task force comprised 21 experts: nurses, occupational therapists, physiotherapists, rheumatologists, orthopaedic surgeons, general practitioner, psychologist, dietician, clinical epidemiologist and patient representatives. After a preliminary literature review, a first task force meeting and five Delphi rounds, provisional recommendations were formulated in order to perform a systematic review. A literature search of Medline and eight other databases was performed up to February 2012. Evidence was graded in categories I–IV and agreement with the recommendations was determined through scores from 0 (total disagreement) to 10 (total agreement). Eleven evidence-based recommendations for the non-pharmacological core management of hip and knee OA were developed, concerning the following nine topics: assessment, general approach, patient information and education, lifestyle changes, exercise, weight loss, assistive technology and adaptations, footwear and work. The average level of agreement ranged between 8.0 and 9.1. The proposed research agenda included an overall need for more research into non-pharmacological interventions for hip OA, moderators to optimise individualised treatment, healthy lifestyle with economic evaluation and long-term follow-up, and the prevention and reduction of work disability. Proposed educational activities included the required skills to teach, initiate and establish lifestyle changes. The 11 recommendations provide guidance on the delivery of non-pharmacological interventions to people with hip or knee OA. More research and educational activities are needed, particularly in the area of lifestyle changes.


Osteoarthritis and Cartilage | 2010

Comparing two low-energy diets for the treatment of knee osteoarthritis symptoms in obese patients: a pragmatic randomized clinical trial

B.F. Riecke; Robin Christensen; P. Christensen; Anthony Leeds; Mikael Boesen; L.S. Lohmander; Arne Astrup; Henning Bliddal

OBJECTIVES To evaluate in a prospective, randomized clinical trial (RCT), symptom response among obese knee osteoarthritis (OA) patients following a feasible, intensive weight-loss program for 16 weeks. METHODS Eligible patients were obese [body mass index (BMI)>30 kg/m(2)]; >50 years old, with primary knee OA. Participants were randomized to either a very-low-energy diet (VLED) or a low-energy diet (LED) (415 kcal/day and 810 kcal/day, respectively), using commercially available formula foods - only for the first 8 weeks, managed by dieticians. The 8 weeks were followed by an additional 8-week period of a hypo-energetic diet consisting of normal food plus meal replacements (1200 kcal/day). The primary endpoint was the number of patients responding according to the Outcome Measures in Rheumatology Clinical Trials and Osteoarthritis Research Society International (OMERACT-OARSI) responder criterion. The statistical analysis was based on a non-responder intention-to-treat (ITT) population (baseline observation carried forward). RESULTS One hundred and ninety two patients (155 (80.7%) females) with a mean age 62.5 years [standard deviation (SD) 6.4; range 50-78 years]; average BMI 37.3 (SD 4.8) were included. At 16 weeks, similar proportions of the VLED and LED groups, 59 (61.5%), and 63 (65.6%) patients, respectively, met the OMERACT-OARSI responder criteria, with no statistical significant difference between the groups (P=0.55). Combining the groups the pooled estimate was 64% meeting the responder criteria [95% confidence interval (CI) 57%, 70%]. There was an overall reduction in pain, corresponding to an average pain reduction on the visual analogue scale (VAS) of 11.1 (95%CI 13.6, 8.5) in the combined groups. At week 16 weight loss in the combined groups was 12.8 kg (95%CI: 11.84-13.66; P<0.001). 71% lost > or =10% body weight in both diet groups, with a pooled estimate of 74% (95%CI: 68-80%). CONCLUSION No clinically significant differences were found between the 415 kcal/day and 810 kcal/day diets. A 16-week formula-diet weight-loss program resulted in a fast and effective weight loss with very few adverse events resulting in a highly significant improvement in symptoms in overweight patients with knee OA.


Osteoarthritis and Cartilage | 2012

Weight loss is effective for symptomatic relief in obese subjects with knee osteoarthritis independently of joint damage severity assessed by high-field MRI and radiography

Henrik Gudbergsen; Mikael Boesen; L.S. Lohmander; Robin Christensen; Marius Henriksen; Else Marie Bartels; P. Christensen; L. Rindel; J. Aaboe; Bente Danneskiold-Samsøe; B.F. Riecke; Henning Bliddal

OBJECTIVE With an increasing prevalence of older and obese citizens, the problems of knee osteoarthritis (KOA) will escalate. Weight loss is recommended for obese KOA patients and in a majority of cases this leads to symptomatic relief. We hypothesized that pre-treatment structural status of the knee joint, assessed by radiographs, 1.5 T magnetic resonance imaging (MRI) and knee-joint alignment, may influence the symptomatic changes following a significant weight reduction. DESIGN Patients were recruited from a Department of Rheumatology. Eligibility criteria were age above 50 years, body mass index ≥ 30 kg/m(2), primary KOA diagnosed according to the American College of Rheumatology (ACR) criteria and having verified structural damage. Patients underwent a 16 weeks dietary programme with formula products and counselling. MRI and radiographs of the most symptomatic knee were obtained at baseline and assessed for structural damage using the Boston-Leeds Osteoarthritis of the Knee Score, minimum joint space width and Kellgren-Lawrence score. Imaging variables, muscle strength and degree of alignment, were examined as predictors of changes in Knee Osteoarthritis Outcome Score (KOOS) and Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) - Osteoarthritis Research Society International (OARSI) Responder Criterion. RESULTS Structural damage at baseline assessed by imaging, muscle strength or knee-joint alignment showed no statistically significant association to changes in KOOS pain and function in daily living (r ≤ 0.13; P>0.05) or the OMERACT-OARSI Responder Criterion (OR 0.48-1.68; P-values ≥ 0.13). CONCLUSIONS Presence of joint damage did not preclude symptomatic relief following a clinically relevant weight loss in older obese patients with KOA. Neither muscle strength nor knee-joint alignment was associated with the degree of symptomatic relief.


Clinical Nutrition | 2009

Bioimpedance vector analysis as a measure of muscle function

Kristina Norman; Matthias Pirlich; Janice Sorensen; P. Christensen; Martin Kemps; Tatjana Schütz; Herbert Lochs; Jens Kondrup

INTRODUCTION The impedance vector produced by an alternating current in the bioimpedance analysis can be seen as a standardised test of cellular mass and function since reactance is believed to reflect the mass and integrity of cell membranes. This study investigated the association between resistance and reactance normalised for height (R/H and Xc/H), and muscle function as assessed by hand grip strength. METHODS 363 patients (172 male, 191 female) from Berlin and Copenhagen were included in the analysis. Whole body impedance was determined by BIA 2000M (Berlin) or EFG2.0 (Copenhagen). Hand grip strength was measured with Digimax electronic hand dynamometer (Berlin) or Jamar dynamometer (Copenhagen). The general linear model was used to assess the association between R/H, Xc/H and hand grip strength. RESULTS We observed a significant association between the impedance parameters R/H and Xc/H and hand grip strength after adjusting for confounding variables (hand grip strength= -36.9 - 0.063 x R/H + 0.573 x Xc/H + 40.7 x Height + 0.115 x Weight - 0.09 x Age + 3.41 (gender=male) + 1.87 (Centre Berlin); Weight: P=0.04, all other coefficients: P<0.0005. r(2)=0.708). CONCLUSIONS The impedance parameters R/H and Xc/H are related to hand grip strength and might therefore be used as a cooperation-independent method to reproducibly assess muscle function.


Arthritis Care and Research | 2015

Effect of Weight Maintenance on Symptoms of Knee Osteoarthritis in Obese Patients: A Twelve-Month Randomized Controlled Trial 1

Robin Christensen; Marius Henriksen; Anthony R. Leeds; Henrik Gudbergsen; P. Christensen; Tina Juul Sørensen; Else Marie Bartels; Birgit F. Riecke; Jens Aaboe; Rikke Frederiksen; Mikael Boesen; L. Stefan Lohmander; Arne Astrup; Henning Bliddal

To compare results of obese patients with knee osteoarthritis (OA) who, after an intensive weight loss regimen, received 1 year of either dietary support (D), a knee‐exercise program (E), or “no attention” (C; control group).


European Journal of Clinical Nutrition | 2012

Improved nutritional status and bone health after diet-induced weight loss in sedentary osteoarthritis patients: a prospective cohort study

P. Christensen; Else Marie Bartels; B.F. Riecke; Henning Bliddal; Anthony Leeds; Arne Astrup; Kaj Winther; Robin Christensen

BACKGROUND/OBJECTIVES:Obese subjects are commonly deficient in several micronutrients. Weight loss, although beneficial, may also lead to adverse changes in micronutrient status and body composition. The objective of the study is to assess changes in micronutrient status and body composition in obese individuals after a dietary weight loss program.SUBJECTS/METHODS:As part of a dietary weight loss trial, enrolling 192 obese patients (body mass index >30 kg/m2) with knee osteoarthritis (>50 years of age), vitamin D, ferritin, vitamin B12 and body composition were measured at baseline and after 16 weeks. All followed an 8-week formula weight-loss diet 415–810 kcal per day, followed by 8 weeks on a hypo-energetic 1200 kcal per day diet with a combination of normal food and formula products. Statistical analyses were based on paired samples in the completer population.RESULTS:A total of 175 patients (142 women), 91%, completed the 16-week program and had a body weight loss of 14.0 kg (95% confidence interval: 13.3–14.7; P<0.0001), consisting of 1.8 kg (1.3–2.3; P<0.0001) lean body mass (LBM) and 11.0 kg (10.4–11.6; P<0.0001) fat mass. Bone mineral content (BMC) did not change (-13.5 g; P=0.18), whereas bone mineral density (BMD) increased by 0.004 g/cm2 (0.001–0.008 g/cm2; P=0.025). Plasma vitamin D and B12 increased by 15.3 nmol/l (13.2–17.3; P<0.0001) and 43.7 pmol/l (32.1–55.4; P<0.0001), respectively. There was no change in plasma ferritin.CONCLUSIONS:This intensive program with formula diet resulted in increased BMD and improved vitamin D and B12 levels. Ferritin and BMC were unchanged and loss of LBM was only 13% of the total weight loss. This observational evidence supports use of formula diet-induced weight loss therapy in obese osteoarthritis patients.


Clinical obesity | 2011

Comparison of a low‐energy diet and a very low‐energy diet in sedentary obese individuals: a pragmatic randomized controlled trial

P. Christensen; Henning Bliddal; B.F. Riecke; Anthony Leeds; Arne Astrup; Robin Christensen

There is no consensus on whether ‘very low‐energy diets’ (VLED; <800 kcal d−1) cause greater weight loss in obese individuals than ‘low‐energy diets’ (LED; 800–1200 kcal d−1). The objective was to determine whether a very low‐energy formula diet would cause greater weight loss than a formula 810 kcal d−1 LED in older sedentary individuals. This is a pragmatic randomized controlled trial. Inclusion criteria: obesity (body mass index [BMI] > 30); age >50 years, with knee osteoarthritis. Participants were randomized to VLED (420–554 kcal d−1) or LED (810 kcal d−1) for 8 weeks, followed by a fixed‐energy (1200 kcal d−1) diet with food and two diet products daily for 8 weeks. In all, 192 participants were randomized. Mean age was 63 years (standard deviation: 6), mean weight 103.2 kg (15.0) and BMI of 37.3 kg m−2 (4.8) at baseline. Mean weight losses in VLED and LED groups were 11.4 kg (standard error: 0.5) and 10.7 kg (0.5) at week 8 and 13.3 kg (0.7) and 12.2 kg (0.6) at week 16. Mean differences between groups were 0.76 kg (95% confidence interval: −0.59 to 2.10; P = 0.27) and 1.08 kg (−0.66 to 2.81; P = 0.22) at 8 and 16 weeks, respectively. Loss of lean body mass was 2.1 kg (0.2) and 1.2 kg (0.4) (17% and 11% of the weight lost, respectively) at week 16 in the VLED and LED group with a mean difference of 0.85 kg (0.01 to 1.69; P = 0.047). Significant adverse effects comparing VLED and LED, were bad breath: 34 (35%) vs. 21 (22%), intolerance to cold: 39 (41%) vs. 17 (18%) and flatulence: 43 (45%) vs. 28 (29%) for VLED and LED at 8 weeks (P < 0.05 in all cases). The VLED and LED regimens were equally successful in inducing weight loss. The significantly lower loss of lean tissue in the LED group together with more frequently reported side effects in the VLED group, favours the choice of low‐energy diet (LED) for the treatment of obesity.


Obesity | 2013

Comparison of three weight maintenance programs on cardiovascular risk, bone and vitamins in sedentary older adults

P. Christensen; Rikke Frederiksen; Henning Bliddal; B.F. Riecke; Else Marie Bartels; Marius Henriksen; Tina Juul-S⊘rensen; Henrik Gudbergsen; Kaj Winther; Arne Astrup; Robin Christensen

Obese patients with knee osteoarthritis (OA) are encouraged to lose weight to obtain symptomatic relief. Risk of vascular events is higher in people with OA compared to people without arthritis. Our aim in this randomized trial was to compare changes in cardiovascular disease (CVD) risk‐factors, nutritional health, and body composition after 1‐year weight‐loss maintenance achieved by [D]diet, [E]knee‐exercise, or [C]control, following weight loss by low‐energy‐diet.


Nutrients | 2017

PREVIEW: Prevention of Diabetes through Lifestyle Intervention and Population Studies in Europe and around the World. Design, Methods, and Baseline Participant Description of an Adult Cohort Enrolled into a Three-Year Randomised Clinical Trial

Mikael Fogelholm; Thomas Meinert Larsen; Margriet S. Westerterp-Plantenga; Ian A. Macdonald; J. Alfredo Martínez; Nadka Boyadjieva; Sally D. Poppitt; Wolfgang Schlicht; Gareth Stratton; Jouko Sundvall; Tony Lam; Elli Jalo; P. Christensen; Mathijs Drummen; Elizabeth J. Simpson; Santiago Navas-Carretero; Teodora Handjieva-Darlenska; Roslyn Muirhead; Marta Silvestre; Daniela Kahlert; Laura Pastor-Sanz; Jennie Brand-Miller; Anne Raben

Type-2 diabetes (T2D) is one of the fastest growing chronic diseases worldwide. The PREVIEW project has been initiated to find the most effective lifestyle (diet and physical activity) for the prevention of T2D, in overweight and obese participants with increased risk for T2D. The study is a three-year multi-centre, 2 × 2 factorial, randomised controlled trial. The impact of a high-protein, low-glycaemic index (GI) vs. moderate protein, moderate-GI diet in combination with moderate or high-intensity physical activity on the incidence of T2D and the related clinical end-points are investigated. The intervention started with a two-month weight reduction using a low-calorie diet, followed by a randomised 34-month weight maintenance phase comprising four treatment arms. Eight intervention centres are participating (Denmark, Finland, United Kingdom, The Netherlands, Spain, Bulgaria, Australia, and New Zealand). Data from blood specimens, urine, faeces, questionnaires, diaries, body composition assessments, and accelerometers are collected at months 0, 2, 6, 12, 18, 24, and 36. In total, 2326 adults were recruited. The mean age was 51.6 (SD 11.6) years, 67% were women. PREVIEW is, to date, the largest multinational trial to address the prevention of T2D in pre-diabetic adults through diet and exercise intervention. Participants will complete the final intervention in March, 2018.


The American Journal of Clinical Nutrition | 2017

Long-term weight-loss maintenance in obese patients with knee osteoarthritis: a randomized trial

P. Christensen; Marius Henriksen; Else Marie Bartels; Anthony Leeds; Thomas Meinert Larsen; Henrik Gudbergsen; B.F. Riecke; Arne Astrup; Berit L. Heitmann; Mikael Boesen; Robin Christensen; Henning Bliddal

Background: A formula low-energy diet (LED) reduces weight effectively in obese patients with knee osteoarthritis, but the role of LED in long-term weight-loss maintenance is unclear.Objective: We aimed to determine the effect of intermittent LED compared with daily meal replacements on weight-loss maintenance and number of knee replacements over 3 y.Design: The design was a randomized trial with participants aged >50 y who had knee osteoarthritis and a body mass index [BMI (in kg/m2)] ≥30. Participants were recruited from the osteoarthritis outpatient clinic at Copenhagen University Hospital in Frederiksberg, Denmark; they had previously completed a 68-wk lifestyle intervention trial and achieved an average weight loss of 10.5 kg (10% of initial body weight). Participants were randomly assigned to either the intermittent treatment (IN) group with LED for 5 wk every 4 mo for 3 y or to daily meal replacements of 1-2 meals for 3 y [regular (RE) group]. Attention by dietitians and the amount of formula products were similar. Primary outcomes were changes in body weight and proportion of participants receiving knee replacements. Outcomes were analyzed on the intention-to-treat-population with the use of baseline-carried-forward imputation for missing data.Results: A total of 153 participants (means ± SDs: BMI: 33.3 ± 4.6; age: 63.8 ± 6.3 y; 83% women) were recruited between June and December 2009 and randomly assigned to the IN (n = 76) or RE (n = 77) group. A total of 53 and 56 participants, respectively, completed the trial. Weight increased by 0.68 and 1.75 kg in the IN and RE groups, respectively (mean difference: -1.06 kg; 95% CI: -2.75, 0.63 kg; P = 0.22). Alloplasty rates were low and did not differ (IN group: 8 of 76 participants; RE group: 12 of 77 participants; P = 0.35).Conclusions: After a mean 10% weight-loss and 1-y maintenance, additional use of daily meal replacements or intermittent LED resulted in weight-loss maintenance for 3 y. These results challenge the commonly held assumption that weight regain in the long term is inevitable. This trial was registered at clinicaltrials.gov as NCT00938808.

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Arne Astrup

University of Copenhagen

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Henning Bliddal

Copenhagen University Hospital

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B.F. Riecke

Copenhagen University Hospital

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Else Marie Bartels

Copenhagen University Hospital

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Anne Raben

University of Copenhagen

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Henrik Gudbergsen

Copenhagen University Hospital

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Mikael Boesen

Copenhagen University Hospital

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