UWL: Association With Outcomes (2009)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To find the underlying factors of weight loss in patients with Parkinson's disease.

Inclusion Criteria:
  • L-dopa-treated patients with Parkinson's disease (minimum of two years of L-dopa treatment)
  • Age- and sex-matched healthy controls
  • All subjects were 60 years of age or older
  • For women, at least five years should have elapsed since menopause and no hormonal substitution.
Exclusion Criteria:
  • Ongoing depression
  • Dementia
  • Gastrointestinal or endocrine disease
  • Ongoing or malignant diseases within five years before the start of the study
  • Other diseases influencing body composition and nutritional status.
Description of Study Protocol:


  • In an initial study, 28 free-living patients with Parkinson's disease and 28 matched controls were studied at the same time of year to avoid seasonal differences
  • Healthy controls were randomly selected from the population register of the catchment area
  • Patients were either already on L-dopa or were given L-dopa and were reinvestigated one and two years later while on L-dopa treatment; two died
  • The results from the present study are from the 26 Parkinson's disease patients and their controls, all of whom had been investigated at year one and two.


Case-control study. 

Statistical Analysis

  • Changes within groups were analyzed by Wilcoxon signed rank test and Student's paired T-test
  • Mann-Whitney U test and Student's unpaired T-test were used to analyze differences between two independent groups
  • Parametric tests were used when the data were normally distributed, tested by skewness analysis, otherwise non-parametric tests were used
  • Stepwise multiple linear regression analysis was performed.
Data Collection Summary:

Timing of Measurements

Cases and controls were assessed twice within a one-year interval.

Dependent Variables

  • Body weight was measured on calibrated analogue Seca scale
  • Body fat mass was assessed by dual X-ray absorptiometry
  • Resting energy expenditure was measured by indirect calorimetry
  • Physical activity assessed by interviews, using questionnaire including seven items about activities: Walks, gymnastics, cycling, climbing stairs, cleaning, cooking or washing and any other physical activity such as gardening, and one item about mobility
  • Dietary data collected using three-day food records
  • Cognitive function assessed using Mini-Mental State Evaluation
  • Serum thyroid-stimulating hormone (TSH), free thyroxine (T4) and free triiodothyronine (T3) hormones were measured by time-resolved fluoroimmunoassay
  • Serum albumin and transthyretin assessed by standard techniques.

Independent Variables

  • Presence of Parkinson's disease: Diagnosed by a specialist in neurology or geriatric medicine
  • Motor symptoms classified according to the Unified Parkinson's Disease Rating Scale.



Description of Actual Data Sample:
  • Initial N: 28 patients with Parkinson's disease, 28 matched controls
  • Attrition (final N): 26 patients with Parkinson's disease and their controls. Two died.
  • Age: Mean age 74.0±5.7 years for patients, 74.0±4.5 years for controls
  • Anthropometrics: Controls were age and sex matched
  • Location: Sweden.
Summary of Results:

Stepwise Multiple Regression Analysis for Weight Loss in Parkinson's Disease Patients




Activity change

0.60 0.001




Age (years) -0.35 0.026
MMSE 0.31 NS
T4 -0.21 NS
Rigidity -0.09 NS
Tremor -0.05 NS

Other Findings

  • 19 (73%) of the Parkinson's disease patients lost body weight (11 females and eight males; mean loss between 0.5kg and 8kg), although energy intake and the time for rest increased
  • Daily recumbent rest increased from 56.5±62.5 minutes at year one to 77.3±80.1 minutes in patients with Parkinson's disease, while in controls it increased from 32.3±43.2 minutes at year one to 33.5±51.2 minutes at year two
  • At year two, the patients with Parkinson's disease had lower body weight, total REE and RQ as well as lower physical activity, and a longer period of recumbent rest during the day compared with controls
  • Weight loss was most marked in patients with more severe Parkinson's disease symptoms and in whom cognitive function had decreased
  • Weight loss was significantly correlated with increased rigidity (P<0.01), decreased tremor (P<0.01), decreased MMSE (P<0.01), decreased physical activity (P<0.01) and increased serum level of T4 (P<0.05)
  • Multiple regression analyses showed that determinants for weight loss were female gender, age and low physical activity: Elderly women with decreased physical activity were most predisposed to weight loss (P<0.0001).
Author Conclusion:

Three of four Parkinson's disease patients lost weight. Elderly women with Parkinson's disease and with low physical activity were prone to lose body weight. An increased energy intake could be an attempt to compensate for the weight loss, a mechanism which was, however, insufficient, as these patients continued to lose weight. Whether or not thyroid dysfunction is of importance cannot be ascertained from the present study. As Parkinson's disease symptoms and decreased cognitive function were more severe in patients with weight loss this could be an expression of a more severe neurodeneration. However, the role of L-dopa treatment per se could not be excluded.

Funding Source:
Government: Health Research Council of Sweden, County Council of Ostergotland
University/Hospital: Linkoping University
Family of Janne Elgqvists Stiftelse, Semper AB Stockholm
Other non-profit:
Other: Stiftelsen Parkinsonforbundets forskningsfond, LIONS in Sweden
Reviewer Comments:

Small numbers of subjects in groups. Authors note the following limitations:

  • Limited number of participants
  • Significant number of analyses performed.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? ???
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? Yes
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes