Exercise as it relates to Disease/Impact of regular physical activity on hospital admissions and mortality in chronic obstructive pulmonary disease

This is an analysis of the study "Regular physical activity reduces hospital admission and mortality in chronic obstructive pulmonary disease: a population based cohort study" by Anto, Benet, Garcia-Aymerich, Lange and Schnohr (2006).

What is the background to this research?
The World Health Organisation defines chronic obstructive pulmonary disease (COPD) as "a lung disease characterized by chronic obstruction of lung airflow that interferes with normal breathing and is not fully reversible". In 2000, approximately 2.7 million deaths occurred as a result of COPD, with a large portion coming from China. The main causes of COPD come from a number of environmental sources with the main being tobacco smoking. Studies in the past have presented a higher prevalence of men suffering COPD when compared to women, recent data from developed countries reveal that the prevalence is now almost equal, underlining possible changing patterns in tobacco smoking.

In 1990, COPD was ranked twelfth in disease burden with an estimated projection to increase significantly by 2020. In 2001, it was the fourth leading cause of death in the world with an estimated increasing trend of mortality, in the USA, death rates are very low in young people but increase significantly in people aged 45 years and older.

COPD is associated with high economic and social costs, so minimizing hospital admissions is of high importance in management of this disease state. A scarce number of previous studies had shown that low levels of physical activities lead to a possible decrease in COPD mortality, this made it worthy to test whether increasing physical activity levels lead to a further decrease in mortality.

Where is the research from?
Anto, Benet, Garcia-Aymerich, Lange & Schnohr recruited a population based sample of people suffering COPD in Copenhagen, Denmark.

What kind of research was this?
This was a population based cohort study, involving participants to self report physical activity levels and analysis of hospital admissions.

What did the research involve?
A population based sample of COPD sufferers was collected in Copenhagen from the years 1981-3 and 1991-3 and followed until 2000. A total of 2386 subjects were included (1100 women and 1286 men), 60 years was the mean age and 71% were current smokers while 12% reported having asthma at some time. COPD diagnosis was determined via lung functioning tests, physical activity levels were self reported based on four categories (very low, low, moderate, high). Hospital admission causes and dates were collected from Danish registers. Negative binomial Cox regression models were used to underline adjusted associations between physical activity and hospital admissions for COPD and mortality.

What were the basic results?
During the mean follow up period of 12.0 years, 60% (1425) of subjects had died while 22% of participants were admitted to hospital atleast once due to the effects of COPD. As predicted, the subjects that had died and been admitted had similar general characteristics. They were generally older, had lower levels of physical activity, more prevalent suffering of Cardiovascular disease, and suffered more severe COPD. Subjects who reported very low physical activity had a higher rate of hospital admission due to COPD than those who reported low, moderate or high levels of physical activity.

How did the researchers interpret the results?
The researchers concluded that there was a correlation between physical activity and a reduction in COPD related hospital admissions and mortality. They found that a relatively small amount of physical activity weekly was enough to significantly reduce burden of COPD. Data collection on physical activity often relies on self report and this study was no exception. Self-reporting is useful for gaining low cost information on large populations, however, there is often a tendency to under or overestimate results. These possible self report errors could have a skewing effect on the results.

What conclusions can be drawn from the research?
This research observed that by completing moderate physical activity (2 hours or more a week) COPD sufferers have a 30 - 40% decrease in hospital admissions and mortality. This can greatly increase quality of life and have a positive impact on hospital costs. Guidelines have been in place recommending that COPD sufferers do exercise regularly, however, these recommendations were not evidence based. The results from this study provide solid evidence that the impact of regular physical activity on COPD sufferers is significantly positive.

What are the implications of this research?
This research provides evidence of management of the irreversible disease state COPD. It presents information that physical activity could be used as a tool to address this growing issue in the elderly population. With estimates that this disease state will increase in prevalence in coming years management strategies and recommendations supported by clear evidence are of high importance.