Exercise as it relates to Disease/Exercise as a means to reduce hospital admission and respiratory mortality due to COPD

This is an analysis of the journal article "Regular physical activity reduces hospital admission and mortality in chronic obstructive pulmonary disease: a population based cohort study".

Background
Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of morbidity and causes of death around the world. COPD affects 6-7% of adults.

COPD is a group of lung diseases that block airflow to the lungs making it difficult to breathe. Reduced airflow and oxygen absorption can affect day-to-day life and physical activity participation.

Unfortunately, information derived from research in relation to regular physical activity and its effect on COPD is scarce.

Current popular guidelines for physical activity for COPD patients is produced by the British Thoracic Society. However the authors of this study state these guidelines do not provide any evidence / research to support them.

For other health conditions such as cancer and Type 2 diabetes, there is significant amounts of research showing higher levels of physical activity (3-5 hours of walking equivalent per week) reduced related risks.

Where is the research from?
The COPD study in question takes a relevant cohort of adults involved in the much larger Copenhagen City Heart Study (CCHS). The CCHS, which commenced in 1976-8, provided relevant historical information for the cohort selected, including the course of COPD.

Funding is provided for the CCHS and grant funding was also provided for the COPD study. The COPD study states the funding did not affect the design and conduct of the research.

The lead author of the paper, Dr J Garcia-Aymerich, is well know for publishing over 100 peer reviewed scientific papers and working with committees tasked with developing international policies on pulmonary rehabilitation.

Study design
The COPD study is a population based cohort study meaning a defined population is followed to determine relationships to risk factors and outcomes.

What did the research involve?
The study participants were a cohort of 2,386 subjects. These participants had originally been recruited to the CCHS from the general population aged 20 years or older. As part of the CCHS, they had undergone repeated examination every 5-10 years. The cohort of participants qualified to be part of the COPD study if they met the criteria for COPD. COPD was defined on the basis of forced expiratory volume in 1 second (FEV1) and forced vital capacity FVC with COPD defined as FEV1/FVC ⩽  70%. The participants were further classified into 4 categories by the degree of airway obstruction as detailed in the table below.

Participants completed a self-administered questionnaire on regular physical activity over the previous 12 months. Details were also obtained of: CCHS staff also provided details of the participants’ health service use over the previous 12 months.
 * current smoking and alcohol consumption;
 * socioeconomic factors (sex, age, education, marital status, cohabitation, income);
 * current symptoms (dyspnoea, sputum, chest pain, leg pain and intermittent claudication); and
 * any diagnosis of co-morbidity (asthma, ischaemic heart disease, myocardial infarction, stroke, diabetes); and

Blood pressure, plasma cholesterol, glucose concentrations, and body mass index were also measured and clinical records were reviewed to obtain information about co-morbidity.

The physical activity questionnaire was originally developed by Saltin and Grimby and has been used in many other studies involving similar populations to describe health outcomes.

The level of physical activity was classified in accordance with the below table. Lung function parameters (FEV1 and FVC) were measured three times with the highest measurements of FEV1 and FVC used in the analysis. Hospital admissions before the start and during the study were obtained as well as causes of death.

A statistical analysis of the data was then undertaken. The analysis took into account the other variables such as COPD severity, age, sex and history of heart disease.

What were the basic results?
The 20 year follow up COPD study results showed that physical activity equivalent to walking of cycling for 2 hours/week or more resulted in a 30-40% reduction in the risk of COPD related hospital admission and respiratory mortality. The participant’s sex, age group, COPD severity or background ischaemic heart disease did not affect this outcome.

The graph to the right is a Kaplan-Meier curve regarding physical activity. Graph A shows time to first COPD hospital related admission during the follow up. Graph B shows time to death (all cause mortality).

After adjusting for cofounders participants reporting low, moderate, or high levels of physical activity had a lower risk of a COPD admission than those reporting a very low level of physical activity.

What conclusions can we take from this research?
Results show that having at least a low level of light physical activity decreases negative outcomes associated with COPD. As the level of light physical activity increases, further reductions in negative outcomes were observed. The type of physical activity required to significantly reduce negative outcomes together with the the activity not requiring specialist supervision makes these findings particularly promising.

The significance of COPD prevalence creates a large socioeconomic burden and results in negative health consequences. Given this, future guidelines for COPD should recommend people with COPD maintain or increase physical activity levels as this is likely to result in improvements for the person as well as overall public health benefits.

Future studies could look at exercise type, frequency, duration and intensity more accurately to guide the public and healthcare providers further.

Practical advice
Any person who has been diagnosed with COPD should be strongly encouraged to undertake at least 2 hours per week of light physical activity. This activity could take the form of walking or cycling, which can be achieved at little or no financial cost.

Where motivation is an issue, it may be joining a group of walkers or cyclists could assist. The inclusion of family members and/or friends in the activity may also result in more consistent participation, as well as increasing the enjoyment of the activity.

Further resources
Exercise tips for people with COPD: my.clevelandclinic.org/health/articles/9450-copd-exercise--activity-guidelines

All things COPD: www.copdfoundation.org/Learn-More/I-am-a-Person-with-COPD/Exercise.aspx