Article Review: “Even a Low Level of Physical Activity Is Associated With Reduced Mortality Among People With Metabolic Syndrome, a Population-Based Study (the HUNT 2 Study, Norway)”

People who do regular physical exercises have lower chances of metabolic syndrome. According to Yoon et al., people with metabolic syndrome are prone to early death caused by chronic diseases such as stroke, heart failure, and diabetes. (1) While a high level of physical exercise is associated with a minimal mortality rate in metabolic syndrome patients, very little is known concerning the effects of low PA levels. In this article, “Even low level of physical activity is associated with reduced mortality among people with metabolic syndrome, a population-based study (the HUNT 2 study, Norway),” Stensvold et al. examine the effects of low PA on the mortality rate of metabolic syndrome patients. (2) Although the authors obtained that a low level of physical exercise is inversely related to the mortality rate of metabolic syndrome patients, the findings had significant limitations related to the design and data collection.

Stensvold et al. conducted this study for approximately three years, from 1995 to 1997 in Nord-Trøndelag County in Norway. Besides, the researchers enrolled 50,339 participants, 13,449 patients with metabolic syndrome, and the rest of the participants without metabolic syndrome. The design of the study was a cohort longitudinal with an extensive health survey. To conduct this study, the researchers used several methods to collect and validate the information. First, the researchers used a questionnaire to collect general information about the participants’ health and PA. Then they excluded participants who had a history of heart disease or missing activity information. Finally, they analyzed the rest of the patients’ information to find the relationship between increased PA and a reduced risk of metabolic syndrome. The researchers found that an increased PA level is associated with a reduced risk of metabolic syndrome. In addition, Stensvold et al. observed that metabolic syndrome patients with a relatively low PA level had a minimal mortality rate than patients who did not have any PA record. Surprisingly, the results had no significant difference between patients with metabolic syndrome and the rest of the participants.

Significant shortcomings were notable in the study design and data collection methods. Firstly, the researchers conducted a population-based study comprising of 50399 people. The participants recorded their PA intensity to help the researchers correlate low-level PA and mortality rate in metabolic syndrome patients. However, the authors did not establish a longitudinal assessment of variables. For instance, they did not consider the changes in the mortality level if the participants’ intensity changed. Besides, the authors could not differentiate the effects of low physical exercise on the metabolic syndrome mortality rate clearly due to other factors that may cause death in metabolic syndrome patients. According to Roman et al., a longitudinal study estimates all the possible causes and effects of changes in variables. (3) Therefore, this study’s findings cannot be reliable. Secondly, the researchers administered questionnaires to the participants to obtain the participants’ marital status, smoking habits, educational level, alcohol consumption, and physical activities. However, the data was self-reported. For instance, the participants’ data on light or hard physical activities, duration of physical exercise, and the intensity of exercises were self-reported. According to Wilson et al., statistical analysis based on self-reports and invalidated scales are likely to have errors that may alter the general findings. (4)Therefore, the use of self-reports undermined the accuracy and reliability of findings. Of course, Stensvold et al. may claim that excluding metabolic syndrome patients with myocardial infarction, angina pectoris, and stroke history enhanced the efficacy of estimating the actual effect of low PA on the mortality rate. Besides, some scholars may argue that the self-reported questionnaires were validated to minimize errors. However, Lee and In, specialists in clinical data analysis and reporting, argue that self-reported questionnaires are always overrated and constitute a significant hindrance to the actual estimation of variables. (5) As such, the authors could have used other analytical measures to minimize the errors.

In conclusion, the finding that a low PA level is linked to a significant reduction of the mortality rate in metabolic syndrome patients was undermined by using self-reports and lack of a longitudinal estimation between variables. The self-reported questionnaires to assess PA duration and the number of PA sessions per week of participants were likely to contain erroneous information, limiting the reliability and generalization of findings. Next, the lack of a longitudinal estimation of variables undermined the establishment of the actual causes of high mortality in patients with metabolic syndrome. Besides, the researchers could not thoroughly examine the changes in results if the patients changed their normal PA duration. Therefore, more studies with accurate data collection mechanisms should be conducted to confirm the findings of this study. In addition, the researchers recommended that patients with metabolic syndrome should increase their PA to reduce the chances of early death.

References

1. Yoon H, Lee JG, Yoo JH, Son MS, Kim DY, Hwang SG, Rim KS. Effects of metabolic syndrome on fibrosis in chronic viral hepatitis. Gut and liver. 2013 Jul;7(4):469. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3724037/
2. Stensvold D, Nauman J, Nilsen TI, Wisløff U, Slørdahl SA, Vatten L. Even a low level of physical activity is associated with reduced mortality among people with metabolic syndrome, a population-based study (the HUNT 2 study, Norway). BMC medicine. 2011 Dec;9(1):1-8.
3. Roman M, Caruana EJ, Hernández-Sánchez J, Solli P. Longitudinal studies. Journal of thoracic disease. 2015 Nov;7(11):E537. Available from: https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4669300/
4. Wilson MG, Gibson TB, Short ME, Goetzel RZ, Pei X, Tabrizi MJ, Ozminkowski RJ, DeJoy DM. How accurate are self-reports? An analysis of self-reported healthcare utilization and absence when compared to administrative data. Journal of occupational and environmental medicine/American College of Occupational and Environmental Medicine. 2009 Jul: 51(7):786. Available from: https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC2745402/
5. Lee S, In J. Statistical data presentation. Korean Journal of anesthesiology. 2017 Jun;70 (3):267. Available from: https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC5453888/