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MNT: Weight Management (2015)

Citation:

Schneider R, Golzman B, Turkot S, Kogan J, Oren S. Effect of weight loss on blood pressure, arterial compliance, and insulin resistance in normotensive obese subjects. Am J Med Sci. 2005; 330(4): 157-160.

PubMed ID: 16234606
 
Study Design:
Before-After Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To assess insulin resistance using the HOMA score and to examine hemodynamic variables and arterial compliance in obese normotensive subjects during a weight management program, including behavioral and pharmacological treatment.

Inclusion Criteria:
  • Normotensive, overweight subjects from the medical staff
  • Fasting glucose level lower than 126mg per dL
  • Blood pressure lower than 140 over 90mm Hg.
Exclusion Criteria:

Subjects with a history of coronary artery disease or peripheral vascular or cardiovascular disease, based on symptoms, physical signs and electrocardiogram.

Description of Study Protocol:

Recruitment

Subjects were recruited from the medical staff as part of a program aimed at encouraging weight reduction among obese members.

Design

Before-and-after study. 

Blinding Used

Implied with laboratory measures. 

Intervention

  • Subjects had personal and group meetings with a physician, dietitian and psychologist to improve their compliance with regard to physical activity and personal low-calorie diet
  • All subjects were instructed on a nutritionally balanced low-calorie diet containing 30% of calories as fat and sodium intake of no more than 80m per Eq sodium per day
  • Patients met the dietitian to assess dietary compliance at baseline and at weeks four, eight and 12
  • Subjects participated in group and individual meetings and were encouraged to perform physical activity to improve their success rate
  • Each subject was given orlistat 120mg three times daily for 12 weeks.

Statistical Analysis

Data were analyzed using paired samples T-test.

Data Collection Summary:

Timing of Measurements

Most measurements made at baseline and after the 12-week study, except for non-invasive hemodynamic parameters measured one month after taking the last dose of orlistat.

Dependent Variables

  • Non-invasive hemodynamic parameters were measured using radial artery pulse wave analysis
  • Fasting plasma glucose and fasting plasma insulin measured
  • Insulin resistance calculated using the HOMA score.

Independent Variables

  • Subjects had personal and group meetings with a physician, dietitian and psychologist to improve their compliance with regard to physical activity and personal low-calorie diet; dietary compliance was assessed through dietitian visits
  • Each subject was given orlistat 120mg three times daily for 12 weeks; compliance was assessed through pill counts. 

 

 

Description of Actual Data Sample:
  • Initial N: 24 subjects were enrolled
  • Attrition (final N): 24 subjects, 3 males, 21 females. 15 subjects took the medication for the entire three months, five stopped taking the medication within two weeks, and four stopped within four weeks due to minor gastrointestinal side effects, but all remained in the study and followed the rest of the program.
  • Age: Mean age, 44±11 years
  • Other relevant demographics: Six were physicians, 18 were nurses
  • Location: Ashkelon, Israel.
Summary of Results:

 

Variables

Before After

P-value

Weight (kg)

89.5±12 81.5±9 P<0.05
BMI 33±4 30±4 P<0.05
Waist circumference (cm) 103±10 94±10 P<0.05
Systolic arterial pressure (mm Hg) 128±12 121±10 P<0.05
Diastolic arterial pressure (mm Hg) 75.4±9 69.6±7 P<0.05
Heart rate (beats per minute) 70±10 64.6±8 P<0.05
Stroke volume (mL per beat per m2) 83±12 87±14 NS
Cardiac output (L per minute) 5.8±0.5 5.7±0.7 NS
Large artery compliance 13±4 15.8±3.6 P<0.05
Small artery compliance 5.9±3.2 5.9±2.8 NS
Total cholesterol (mg per dL) 206±40 185±31 P<0.05
Triglycerides 134±32 109±27 P<0.05
LDL 140±27 116±32 P<0.05
Insulin, μU per mL 14±8 12±6 P<0.05

HOMA score

6.5±4.5

4.8±3.1

P <0.05

Other Findings

At the end of the three-month period, the average weight was reduced from 89.5±12kg to 81.5±9kg (8kg, 9% weight loss).

The systolic arterial pressure was reduced from 128±12mm Hg to 121±10mm Hg and diastolic arterial pressure was reduced from 75.4±9mm Hg to 69.6±7mm Hg.

Arterial compliance measurements showed significant improvement in large artery compliance from 13±4 to 15.8±3.6 while no change occurred in small arteries.

The insulin sensitivity assessed by HOMA score improved significantly from 6.5±4.5 to 4.8±3.1 with weight reduction. 

Author Conclusion:

In conclusion, obesity in normotensive patients is not accompanied by a decrease in arterial compliance, as has been previously suggested by several investigators. We have shown here that weight reduction, by any means, leads to reduction in arterial pressure even in normotensive obese subjects. Because of the reduced blood pressure, large artery compliance improves. However, the small artery compliance, which was not impaired to begin with, was not increased by weight reduction.

Funding Source:
University/Hospital: Ben Gurion University Barzilai Medical Center Campus, Ashkelon, Israel
Reviewer Comments:

Small number of subjects in groups, recruited from medical staff. Only 15 subjects took the medication for the entire three months. Authors note that because nine subjects did not receive the orlistat for one month and because the second hemodynamic evaluation was performed at least one month after cessation of treatment, the hemodynamic changes were related to the weight loss and not the pharmacological treatment.

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) Yes
  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) Yes
 
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? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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.) N/A
  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? 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? N/A
  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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  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? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? N/A
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? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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