UWL: Association With Outcomes (2009)

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

To investigate food habits and nutrient intake in elderly Parkinson's disease patients compared with matched controls, as well as to compare Parkinson's disease patients with and without weight loss.

Inclusion Criteria:
  • Free-living elderly, 60 years or older
  • For women, five years post-menopause, with the exception of those taking hormonal replacement therapy
  • Participants taking vitamin B12 supplements
  • Patients with Parkinson's disease
  • Healthy controls.
Exclusion Criteria:
  • Patients with ongoing depression, dementia, gastrointestinal or endocrine disease, or malignant disease within five years prior to the start of the study
  • Patients with other diseases influencing body composition and nutritional status.
Description of Study Protocol:


  • Subjects were consecutively enrolled from geriatric and neurological outpatient departments during a period of three years
  • Healthy controls were randomly selected from the regional population register of the same geographical area.


Longitudinal case-control study. 

Statistical Analysis

  • Differences between Parkinson's disease patients and controls, as well as changes within groups, were analyzed by Student's paired T-test, Wilcoxon signed rank test and McNemar
  • Student's unpaired T-test, Mann-Whitney U test and chi-squared test were used to analyze differences between two independent groups
  • Parametric tests were used when the data were approximately normally distributed and tested by skewness analysis; otherwise, nonparametric tests were used.
Data Collection Summary:

Timing of Measurements

  • Cases and controls assessed twice with one-year interval in between
  • Controls were investigated at the same time of year to avoid seasonal differences.

Dependent Variables

  • Food habits and qualitative classification of meals and snacks were assessed with the Food-based Classification of Eating Episodes
  • Dietary intake recorded over three consecutive days and intakes of energy and nutrients were calculated
  • Energy requirements: BMR predicted using WHO-FAO-UNU equations
  • Parkinson's disease symptoms: Assessed through the use of the Unified Parkinson's Disease Rating Scale
  • Olfactory ability graded as normal, mildly reduced or much reduced
  • Swallowing function assessed using a seven-grade scale from normal function to severe dysphagia 
  • Daily activity: Subjects were interviewed about their regular activity and assessed with a questionnaire, which had been modified for the current study 
  • Social factors: Participants were interviewed about their living situation and the extent to which they required help from the home-help service
  • Serum concentrations of nutrients: 25-hydroxyvitamin D, vitamin B12, folate, albumin, transthyretin, hemoglobin and calcium.

Independent Variables

Presence of Parkinson's disease.


Description of Actual Data Sample:
  • Initial N: 26 cases with Parkinson's disease (17 females, nine males), 26 healthy controls
  • Attrition (final N): As above
  • Age: Mean age 74 years (74±5.7 years for cases, 74±4.5 years for controls)
  • Anthropometrics: Controls were sex- and age-matched
  • Location: Sweden.
Summary of Results:

Parkinson Symptoms at Years One and Two in Patients with Parkinson's Disease with and Without Weight Loss

Unified Parkinson's Disease Rating Scale (Score)

Parkinson's Disease with Weight Loss (N=19)

Year 1

Parkinson's Disease with Weight Loss (N=19)

Year 2

Parkinson's Disease Without Weight Loss (N=7)

Year 1

Parkinson's Disease Without Weight Loss (N=7)

Year 2

Mentation, behavior and mood (one to four)

1.0±1.5 1.8±2.8, P<0.05 1.7±1.8 2.4±2.7

ADL (five to 17)


10.8±9.0, P<0.05


Salivation (six) 0.65±0.9 0.60±0.7 1.0±1.0 1.0±1.0
Motor symptoms (18 to 31) 18.5±10.2 22.5±13.9, P<0.01 14.0±11.3 16.7±11.5

Other Findings

  • At year one, there was no significant difference in body weight between Parkinson's disease patients and their controls, but one year later the Parkinson's disease patients had a significantly lower body weight (65.1±11.7kg) compared with controls (71.6±11.1kg, P<0.05)
  • 19 Parkinson's disease patients lost weight, from 66.4±11.2kg to 63.3±12.8kg (P<0.001) and their BMI decreased from 24.6±2.8 to 23.2±3.4 between the two investigations (P<0.01)
  • In the other seven Parkinson's disease patients, there was an increase in body weight from 68.3±6.7kg to 70.1±6.3kg (P<0.05) and BMI from 25.8±2.7 to 27.0±3.2 (P<0.05)
  • No significant changes in weight were found within the control group
  • More of the Parkinson's disease patients had impaired olfaction (P<0.001) and dysphagia (P<0.01) compared with controls
  • After one year, the Parkinson's disease patients decreased their intakes of daily high-quality snacks from 0.5±0.7 to 0.3±0.3 (P<0.05) and their prepared complete meals from 0.8±0.3 to 0.6±0.3 (P<0.05), while their daily number of prepared incomplete meals increased from 0.2±0.2 to 0.3±0.3 (P<0.01)
  • Parkinson's disease patients with weight loss increased their daily intakes of fat by 12±34g and their energy intake per kg body weight increased by 21±31kJ (P<0.05), respectively, and this was higher than in those without weight loss (P<0.01)
  • Parkinson's disease patients required more help with buying and cooking food compared with the controls. 
Author Conclusion:

Food habits of patients with Parkinson's disease changed towards consumption of fewer prepared complete meals. A higher intake of fat and energy was seen in weight-losing Parkinson's disease patients, although obviously not sufficient to prevent weight loss. Weight loss in spite of increased intake of fat may be an expression of impaired absorption and that Parkinson's disease is a more general disease than has previously been assumed.

Funding Source:
Government: Health Research Council, County Council of Ostergotland
University/Hospital: Health Science University of Linkoping, Sweden
LIONS in Sweden
Other non-profit:
Reviewer Comments:

Relatively small numbers of cases and controls, resulting in even smaller numbers of patients with Parkinson's disease, with and without weight loss. Some measurement methodologies were not shown to be valid and reliable. Authors note the following limitations:

  • Small number of patients
  • Patients in this study were tired; food records are arduous and time-consuming
  • Possibility of misreporting.
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? N/A
  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? ???
  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.) ???
  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? ???
  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? ???
  7.5. Was the measurement of effect at an appropriate level of precision? ???
  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)? ???
  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