Exercise as it relates to Disease/Reduced all cause mortality with increased physical activity in Chronic Obstructive Pulmonary Disease patients

This is an analysis of the journal article "Changes in physical activity and all-cause mortality in Chronic Obstructive Pulmonary Disease" by Anouk W. Vaes.

What is the background to this research?

Chronic Obstructive Pulmonary Disease (COPD) describes an umbrella term consisting of one or more of the following conditions:

• Emphysema
• Chronic Bronchitis
• Chronic Asthma

COPD develops as a result of consistent inhalation of pollutants such as smoking, passive smoking and pollutants found at workplaces such as chemicals, fumes and dust. COPD sufferers experience dyspnea (shortness of breath), which stems from gradual narrowing of the bronchial tubes that feed air in and out of the lungs, making it difficult to breathe. Sufferers often relate shortness of breath to their age resulting in a gradual decline in physical activity overtime due to the discomfort COPD sufferers experience when exercising. This continual decline in physical activity continues until everyday tasks such as getting out of bed, dressing and showering become almost impossible.
Prevalence
Lung Function Australia estimated that in 2016, 1.45 million or one in seven people suffer from some form of COPD. In 2010, COPD was the third leading cause of death worldwide.

Where is this research from?

Anouk W. Vaes from the Centre of Expertise for Chronic Organ Failure (CIRO) conducted this study throughout Western Europe, in particular Copenhagen City of Denmark and Horn of Netherland.

What kind of research was this?

This study is a Retrospective Cohort Study. Retrospective Cohort Studies look to follow a group of participants for a period of time who already suffer from a disease. The researcher analyses how a disease changes overtime as a result of a stimulus. The data collected for the experiment was done using a self-report questionnaire of physical activity level and a physical examination of lung function through Spirometry testing.

What did the research involve?

Participants who were involved in a separate study called Copenhagen City Heart Study conducted by Dr Peter Schnohr, were invited to participate in Anouk W. Vaes’ research study. Anouk W, Vaes excluded participants from the study who had missing data or those who had inconsistent diagnosis of COPD. A total of 10,004 subjects were analyzed, 1,270 subjects with COPD and 8,734 without COPD. A baseline examination was conducted constituting of a self-report questionnaire on current physical activity levels and a physical examination of lung function using a Spirometry test. Participants were told that follow-up examinations would be required in future, they were not specifically told to increase or decrease fitness levels. The follow-up examinations were conducted in an identical manner to the baseline examination. The median time between baseline examination and follow-up examination was 9 (5-11) years. 5,408 subjects had one follow up examination, 2,537 subjects had two follow-up examinations and 2059 subjects had three follow-up examinations.

What were the basic results?

Table 1a 'Changes in all cause mortality risk from baseline to follow-up examinations'

Physical activity changes over course of the study	Changes in all cause mortality risk in subjects with COPD	Changes in all cause mortality risk in subjects without COPD
Baseline Low → Follow-up Moderate/High	Increased	Reduced
Baseline Low → Follow-up Low	Increased	Increased
Baseline Moderate/High → Follow-up Low	Increased	Increased
Baseline Moderate/High → Follow-up Moderate/High	Reduced	Reduced

Subjects with COPD not only reported a lower physical activity level at baseline compared with subjects without COPD, they were more likely to decrease their physical activity levels overtime. This decrease in physical activity can be linked back to the adverse symptoms COPD sufferers experience with exercise. Subjects without COPD who had a decline in physical activity at follow-up had a higher all cause mortality risk than subjects who maintained or increased physical activity participation. However this was not the case for COPD subjects. COPD subjects who self-reported low baseline physical activities and who increased physical activity at follow-up, did not see a reduction in all cause mortality risk.
Limitations of Study
Like all studies this study incorporates some unreliable methods that may impact validity of the results. Self-reporting of physical activity levels is often over reported, meaning people say they partake in more physical activity then they realistically do. This study needed valid physical activity reporting to ensure results were as reliable as possible. For example, those subjects who reported low baseline and moderate to high follow-up physical activity levels may have felt a sense of guilt or embarrassment that they hadn’t improved their physical activity participation. This may have led them to over report in the follow up examination. This could be the reasoning behind increased all cause mortality even though subjects said they increased physical activity. Another limitation in this study is the inconsistent time period between baseline examination and follow-up examinations. The study states that the median time between the two examinations was 9 (5-11) years. To ensure valid results the subjects needed to be re-examined at the same time point.

What conclusions can we take from this research?

This particular study concludes that earlier participation in physical activity and maintaining physical activity over time can reduce all cause mortality. However, if sufferers do not participate in physical activity to then begin exercise, there is no reduction in all cause mortality. There have been minimal studies conducted looking at exercise and how it affects people living with COPD. However, the studies that have been conducted have all produced similar findings in that COPD is irreversible. Research suggests though, COPD sufferers can better manage their condition in an attempt to avoid adverse events such as hospitalisations1.

Practical Advice

This study examined the impact of exercise in relation to all cause mortality risk in people with and without COPD. Researchers should consider conducting studies to analyse the effect of exercise on lung function in people with COPD. Future studies should consider moving away from self-report methodology as it has the potential for false reporting. Physical examination of fitness through anaerobic and aerobic testing would be a more appropriate and reliable way of analyzing fitness levels. Another avenue for future research would be to distinguish was sort of training (aerobic, resistance, plyometric) possess the biggest improvements in sufferers. In conclusion, the research that has been conducted suggests that people who are at risk of developing COPD should begin regular physical activity as early as possible to avoid adverse events and live a good quality life. The longer a COPD sufferer remains physically inactive the potential for them to reduce their all cause mortality is minimal even if they begin exercising.

Further Information

For further information regarding Chronic Obstructive Pulmonary Disease; click on the links below:

• Inadequate energy supply to respiratory and locomotor muscles in COPD patients: http://jap.physiology.org/content/105/2/749.short
• Relationship between gender and smoking on development of COPD: http://erj.ersjournals.com/content/10/4/822.short
• Relationship between exercise capacity and health status to mortality in patients with COPD: http://www.atsjournals.org/doi/full/10.1164/rccm.200206-583OC#.V-dm18dYm1s