Research Critique
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Research Critique



I critiqued a research article to see if it was able to convey a strong link between heart disease and sleep apnea.

I critiqued a research article to see if it was able to convey a strong link between heart disease and sleep apnea.



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Research Critique Research Critique Presentation Transcript

  • Research Article Critique
    Kayla Muth
  • Article Overview
    Prospective Study of Obstructive Sleep Apnea and Incident Coronary Heart Disease and Heart Failure: The Sleep Heart Health Study
    Study began in 1994 and ended in 2006
    Submitted August 2009
    Accepted May 2010
    Published in Circulation July 2010
  • Sources
    Publication dates ranged from 1975-2009
    Selection of Journals and Studies
    American Journal of Cardiology
    American Journal of Medicine
    Framingham Heart Study
    Journal of the American Medical Association
    Journal of Applied Physiology
    New England Journal of Medicine
  • Definitions
    Obstructive Sleep Apnea (OSA)
    Continuous Positive Airway Pressure Therapy
    Community Based Prospective Cohort Study
    Chin electromyogram
    Inductance plethysmography
    Apnea-hypopneaindex (AHI)
    Incident CHD
    Incident Heart Failure
    Cox proportional hazards regression modeling
    Linear regression splines
    Adjusted hazard ratio
  • Purpose of the Study
    “To assess the independent contribution of OSA to cardiovascular disease, the Sleep Heart Health Study (SHHS) was initiated in 1994 as a multicenter, prospective cohort study of the cardiovascular consequences of OSA.”
    “The present report details the incidence of CHD and heart failure in SHHS participants free of these conditions at the baseline examination.”
  • Study Design
    Adults 40 years of age and older were recruited from existing population-based studies of cardiovascular and pulmonary disease
    Participants completed questionnaires on sleep habits and general health
    Height, weight, and blood pressure were measured
    Underwent overnight polysomnography
    Parent cohorts provided data
    Ongoing surveillance for cardiovascular disease through April 2006
  • Study Sample
    10,737 cohort participants invited to participate
    6,441 were enrolled in study
    760 participants from NYU-Cornell site excluded
    783 participants excluded due to prevalent heart disease or heart failure at baseline
    21 participants lacked follow-up data and were excluded
    455 participants were missing baseline measures and excluded
    4,422 subjects remained for participation
    2,495 females
    1,927 males
  • Methods
    In-home polysomnography
    Polysomnograms scored centrally and AHI determined
    Ongoing surveillance for CHD and heart failure by parent-cohorts
    Follow-up procedures performed by cohorts
    Median follow-up ranged from 8.3-9.2 years
    All CHD and heart failure outcomes extracted from hospital and physician’s records by trained abstractors
    ~5 years post-baseline, survey relative to diagnosis of and treatment for OSA completed by 3,794 participants
  • Covariates
    Baseline prevalent CHD or heart failure
    Smoking status
    Blood pressure
    Total cholesterol
    HDL cholesterol
  • Statistical Analysis
    Performed with SAS version 9.2
    Descriptive statistics presented by category of OSA severity based on the AHI
    Testing for improved model fit
    Cubic or quadratic functions
    Linear regression splines
    Association between sex and AHI
    Models created for males and females
  • Statistical Analysis cont.
    Models using AHI as continuous dependent variable adjusted for the following independent variables:
    (1) Age, race, BMI, and smoking status
    (2) Variables from model (1) plus total and HDL cholesterol and diabetes
    (3) Variables from model (2) plus hypertension
    Models repeated using parent cohort instead of race
    Models constructed to stratify age
    >70 years old
    ≤ 70 years old
  • Results
    Increasing severity with OSA was associated with male sex, higher BMI, higher systolic blood pressure, lower HDL cholesterol, and higher prevalence of hypertension and diabetes
    Median AHI in women was 2.7 (interquartile range 0.8 to 7.5) and 6.2 in men (interquartile range 2.3 to 14.3)
    During follow-up period there were 473 incident CHD events
    76 CHD deaths
    185 MI’s
    212 revascularization procedures
  • Results cont.
    During follow-up there were 308 incidents of heart failure; 144 also had incident CHD
    Rate of events increased with severity of OSA in men, but not as clearly in women
    When adjusted for age, race, BMI, and smoking status there was a significant association between AHI with incident CHD in men
  • Discussion
    This study found an association between incident CHD and OSA in men that was considerably weaker than previous clinic-based studies
    Screening of non-clinic-based population identified many asymptomatic individuals with OSA
    SHHS may underestimate the true cardiovascular risk associated with OSA due to median age of 62
    Study demonstrates a 58% higher adjusted risk for incident heart failure for men with OSA
  • Strengths
    Community-based recruiting limited referral bias
    Detailed covariate data
    Exclusion criteria provided
    Few received treatment for OSA allowing for assessment of natural history of untreated OSA
    Includes both men and women
    Ethnically diverse
  • Weaknesses
    Older age of the cohort
    Echocardiograms were not routinely performed
    Varying protocols at different facilities
    Varying frequency of follow-ups
    Authors do not appear to be individuals who extracted data from medical records
    BMI is imperfect way to collect anthropometric data
    Diet and exercise not recorded
  • Significance
    Potentially significant because it does suggest an increased risk of incident heart failure in those with OSA
    Those with OSA tend to have all other risk factors predisposing them to heart disease, so it is hard to demonstrate if OSA has significant impact independent of those risk factors