Journal Club Synopsis-Wellness. November 29, 2012
Kudos to the resident presenters: Mark Hemming, Maggie Putman, Sola Balogun, Steve Walchuk, Brad Kutka and Bret Negro. Also, many thanks to Dr. John Principe and his staff at the WellBeingMD Center.
Article 1: Mitrou PN, et al: Mediterranean dietary pattern and prediction of all-cause mortality in a US population: results from the NIH-AARP Diet and Health Study. Arch Intern Med. 2007 Dec 10;167(22):2461-8.
This prospective observational study was a 1995 survey of 380,296 people with no history of chronic disease as part of the National Institutes of Health-AARP Diet and Health Study. The questionnaire asked about conformity with the Mediterranean dietary pattern (emphasis on vegetables, fruits, nuts, legumes, whole grains, fish, olive oil). Conformity with the Mediterranean diet was associated with significantly reduced all-cause and cause-specific (cardiac and cancer) mortality at 5 and 10 years. In men, hazard ratio comparing high to low diet conformity for all-cause mortality was 0.79 (95% CI, 0.76-0.83). For women, high conformity with the diet was associated with a 20% decreased risk for all-cause mortality. Multivariate models attempted to adjust for potential confounding mortality risk factors. Results were maintained in participants who had never smoked, and for both genders.
Both Mark and Maggie mentioned issues of recall bias (how accurately the diet survey was filled out), and Dan stressed that although the trial tried to correct for confounders, there are still likely additional positive choices that people eating a healthy diet make that also contribute to their overall state of health. Chintan pointed out that participants were only surveyed once, and diet popularity often changes over time; no way of knowing if they complied with the Mediterranean diet for 10 years. Bottom line for the presenters-the results are consistent with other studies of the Mediterranean diet. The diet is easy to remember and worth sharing with patients, family.
Article 2: Kodama S, et al: Cardiorespiratory Fitness as a Quantitative Predictor of All-Cause Mortality and Cardiovascular Events in Healthy Men and Women; A Meta-analysis. JAMA. 2009;301(19):2024-2035.
This laborious meta-analysis attempts to quantify the relationship between cardiorespiratory fitness (CRF) and all-cause mortality as well as coronary heart disease (CHD)/cardiac events in healthy participants. Data were obtained from 33 eligible studies of > 185,000 participants. Compared with participants with high CRF, those with low CRF had a relative risk for all-cause mortality of 1.70 (95% CI , 1.51-1.92; p<0.001) and for CHD/cardiac events of 1.40 (95% CI, 1.32-1.48; p<0.001). A 1-MET (1 km/hour higher jogging speed) increased level of maximal aerobic capacity was associated with 13% and 15% decreases in risk for all-cause mortality and CHD/cardiac events respectively. This study suggests that cardiorespiratory fitness could be integrated into the risk factor profile for CHD, and establishes the minimal walking speeds or Bruce protocol performance for men and women at various ages that may help prevent CHD.
Harwood liked the outcome measure of all-cause mortality: you don’t want to decrease cardiac mortality but increase the mortality from falling off treadmills.
Stats pearl: There was a lively discussion of the applications of various study methodologies. As Barounis stated, a RCT evaluates one variable and one outcome and in general provides the highest level of evidence. Observational cohort studies don’t examine cause and effect, and can’t account for all confounders. So, an excellent RCT will trump a meta-analysis and certainly trump an observational trial. At the same time, for this evening’s clinical questions (diet, exercise), prospective observational cohort trials may be the most appropriate and ethical trial design. Randomizing anybody to the “high saturated fat sessile lifestyle” arm isn’t going to make it past an IRB. Another great example from Harwood-you’re not going to perform a RCT on the safety of motorcycle helmets-it’s going to be a population study.
Or from a Bayesian (E. Kulstad): it’s situational-for these questions, our pre-test probability is already weighted. For diet, if the alternative hypothesis is that a McDonald’s diet is the same or better than Mediterranean, well nobody’s saying that. Even before seeing the data, you have an established pre-test probability.
So even with their limitations, a prospective observational cohort trial is a satisfactory trial design for certain questions, and as Sola said, a well done meta-analysis of high quality observational trials can provide very useful information.
Article 3: Bowen S, Marlatt A: Surfing the urge: brief mindfulness-based intervention for college student smokers. Psychol Addict Behav. 2009 Dec;23(4):666-71.
Mindfulness, or an attentive awareness especially of the present moment, is an important part of Buddhist teachings. More recently, the concept has been incorporated into western therapies for treatment of mental illness and drug addiction. This RCT examined effects of a brief mindfulness technique on smoking behavior among nicotine-deprived college student smokers. A total of 123 participants either received instructions on the technique or were advised to use their own coping skills after being deprived of cigarettes for 12 hours and then taunted with cigarettes. Primary outcome was the number of cigarettes smoked over the 7-day follow-up period, and the intervention group on average smoked 1.5 fewer cigarettes. How does it work? Bret-it’s all about acceptance, giving up control. By observing negative feelings or urges without reacting, participants may learn alternative responses to negative experiences.
Lots and lots of problems with the study: small group sizes, short follow-up, everything was self reported, these were college psychology students with low levels of nicotine addiction and were light smokers (not necessarily externally valid when thinking about our patient population), questionable clinical significance (decrease of 1.5 cigarettes), and they didn't query the intervention group to see if they even used the mindfulness technique. There is also the well described unconscious desire to please the investigator by providing the “correct” answers on a follow-up survey. Bottom line-even with the limitations, it’s an intriguing low cost concept, and for our patients, would be interesting to see it studied as part of a more comprehensive smoking cessation program.
Finally, a few comments from Dr. Principe. He encouraged reinforcement of the positive as a means of sustaining behavior change, rather than emphasizing denial and deprivation. He advocates mindfulness and appreciating/living in the moment, nutritional education, and exercise as components of overall good health. He stressed the importance of “moving along the spectrum”: we can’t take our population abruptly to an Ornish or Mediterranean lifestyle. He recommends the book The Blue Zones by Dan Buettner, published by National Geographic, as an exploration of the factors that contribute to certain populations around the world leading extraordinary long, healthy lives.