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HTN: Alcohol (2015)

Citation:
Baros AM, Wright TM, Latham PK, Miller PM, Anton RF. Alcohol consumption, %CDT, GGT and blood pressure change during alcohol treatment. Alcohol and Alcoholism, 2008; 43 (2): 192-197. PubMed ID: 18039674
 
Study Design:
Before-After Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To examine the changes in blood pressure of alcohol dependent individuals over time in relation to alcohol drinking status as well as biological markers of alcohol consumption.
Inclusion Criteria:
  • Alcohol-dependent patients participating in a randomized clinical trial of treatment therapies (Anton et al, 2005)
  • Dependent on alcohol but not other substances (except nicotine)
  • Absence of major psychiatric illness
  • Medically stable
  • Liver enzymes ALT and AST less than 2.5 times the upper limit of normal.
     
Exclusion Criteria:
  • Major psychiatric illness
  • Other substance dependence (except nicotine)
  • Medically unstable
  • Liver enzymes ALT and AST 2.5 or more times the upper limit of normal.
Description of Study Protocol:

Recruitment

Subjects utilized were those recruited for the Anton et al, 2005, study of therapy treatment for alcohol dependency. Subjects were randomized into two treatment therapies for that study.

Design

  • A prospective cohort of only the subjects with hypertension participating in a randomized trial
  • Subjects were evaluated for alcohol use at baseline and at the end of Weeks Two, Six and 12
  • Blood pressure (BP), blood for liver function tests (ALT and AST), biomarkers of alcohol consumption (%CDT and GGT) and self-reported alcohol consumption measures were obtained at each visit.

Blinding Used

Implied with measurements.

Intervention

Study subjects were participants in a 12-week alcohol relapse prevention study.

Statistical Analysis

  • All baseline variables were examined for predictive validity of pre-study systolic blood pressure (SBP) and diastolic blood pressure (DBP) by linear regression analysis
  • During the trial, the impact of drinking status on BP at Week 12 and the relationship of biomarkers (%CDT and GGT) to BP were analyzed by ANCOVA, with study entry BP as a covariate
  • Spearman's Rho (non-parametric analysis) was used to determine the relationship between percentage change in BP, GGT and %CDT over the course of 12 weeks
  • All analysis were conducted using the statistical package for social sciences (SPSS).
Data Collection Summary:

Timing of Measurements

Measurements taken at baseline, two, six and 12 weeks.

Dependent Variables

  • Blood pressure taken by the same electronic BP monitoring device (DINAMAP ProCare 120) that was calibrated every six months for accuracy. BP was taken while seated.
  • Percentage CDT was measured by micro-column separation and ELISA assay method using test kits from Biorad Inc.; inter- and intra-assay coefficients of variation were below 10%
  • GGT was measured using Abbot Aeroset auto-analyzer with inter- and intra-coefficient variations below 5%.

Independent Variables

  • Alcohol consumption was measured by a calendar based self-reporting procedure, using the timeline follow-back method for the specified time (seven to 90 days)
  • Mnemonics such as holidays and special dates were used
  • Standardized glass examples and volumes were used to quantify daily consumption.

Control Variables

All subjects were enrolled in an outpatient alcohol treatment program, ensuring a recent, significant alcohol intake history at baseline.
Description of Actual Data Sample:
  • Initial N: 160 participants in the randomized trial (gender not reported); 120 participants had hypertension
  • Attrition (final N): 120 participants had hypertension (93 male, 27 female)
  • Age: 44±9 years of age
  • Ethnicity: 86.7% white, 13.3% non-white (not described).

Other Relevant Demographics

57% were married.

Anthropometrics

  • 15±7 alcohol dependence scale
  • 12±6 drinks per drinking day past 90 days
  • 74±23% days heavy drinking past 90 days
  • 873±549 standard drink units past 90 days
  • 26±4 kg/m2 Body Mass Index (BMI)
  • 53% nicotine use.

Location

Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC.

Summary of Results:

Key Findings

Predictive validity of baseline characteristics (significant findings)

  • DBP
    • Gender was a predictor of DBP at baseline (P=0.02)
    • BMI was correlated with DBP (R=0.24, P=0.009).
  • SBP
    • Age increased with increasing SBP (P=0.03)
    • BMI was correlated with SBP (R=0.28, P=0.002).
Total abstinence vs. any drinking on BP (significant findings)
Total abstinence decreased SBP by 10mmHg (P=0.003) and SBP by 7.0mmHg (P=0.001).

Overall BP and biological markers of alcohol consumption over time (zero, six and 12 weeks)
  • BP and both biological markers of alcohol consumption demonstrated a significant reduction over time (P<0.001)
  • Reduction in percentage CDT and GGT were most pronounced between Weeks Zero and Six (P<0.001).
High and low biological variables at Week 12
  • Participants with negative (normal) percentage CDT or GGT had lower BP than those with higher percentage CDT or GGT
  • Significant difference between positive and negative percentage CDT (df1, F=6.73, P=0.01) on SBP
  • Significant difference between positive and negative percentage CDT (df1, F=9.35, P=0.03) and GGT (df1, F=4.62, P=0.03) on DBP.
Relationship between change in SBP and DBP and change in %CDT and GGT at baseline and Week 12
  • Change in percentage CDT and change in SBP (P=0.003; Rho, 28) and DBP (P<0.0001; Rho, 34)
  • Change in GGT and change in SBP (P>0.05; Rho, 0.09) and DBP (P=0.03; Rho, 0.20).
Author Conclusion:
  • This study shows that a reduction in alcohol in heavy drinkers is associated with a reduction in measured blood pressure and biological markers of alcohol consumption over the course of the 12-week study
  • Participants who kept total abstinence to alcohol had significant reduction in both systolic and diastolic blood pressure over those who had any drinking. These results support the recommendation that alcohol-dependent individuals could reduce blood pressure with abstinence.
Funding Source:
Government: Grant from National Institute on Alcohol Abuse and Alcoholism
Reviewer Comments:
  • Intent-to-treat analysis (N=160) was conducted and no difference in demographic and baseline characteristics existed
  • 17 of 120 participants reported using anti-hypertensives by the end of the study, although the changes in demographics, BP and biomarkers was not statistically significant.
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? No
2. Was the selection of study subjects/patients free from bias? Yes
  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? 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? Yes
  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? N/A
  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? Yes
  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? 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? 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? 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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  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