A new study1 evaluating the effect of inhaled corticosteroids for people with chronic obstructive pulmonary disease (COPD) suggests the medications can truly be beneficial, confirming the findings of previous research that some medical experts charged may have been biased.
Circumventing Bias
Doctors in the latest research used two study designs to eliminate the potential for immortal time bias. This is a research bias that occurs when investigators assess the benefit of a particular drug in question after a patient using the medication dies, meaning that those who survive have a potentially greater amount of time to continue using the drug in question. This leads to potentially overestimating the effectiveness of the medication.2
To avoid such bias in evaluating inhaled corticosteroids as therapy for COPD, Joan Soriano, MD, PhD, of Worldwide Epidemiology at GlaxoSmithKline Research and Development in Collegeville, Pennsylvania and her associates undertook two studies. The first created two matched sets of patients based on medical records they obtained from a research database. One set of 393 patients had been hospitalized for a COPD-related condition over a nine-year period, collectively, and had been treated with ICSs. The second group of 393 patients had not been treated with the medication.
A second study by the researchers was an analysis of 2,000 patients designed without regard to ICS use. Each patient who had died or was re-hospitalized because of COPD was compared to four patients who did not die or were not re-hospitalized.
All the patients had been monitored for a year after discharge from a hospital for COPD.
Inhaled Steroid Use Reduced Risks
After evaluating all the data, Soriano and her team determined in both studies that there was approximately a 30% lower risk of COPD-related death or re-hospitalization associated with inhaled corticosteroid use over a 1-year period.
"With different study designs reducing potential bias, we consistently found an association between ICS use and the reduction of risk of re-hospitalization and death," Soriano said.
A Disease of Smoking
COPD is considered the fourth leading cause of death in the United States and around the world. It is a collective term used to describe various lung diseases, mainly emphysema and chronic bronchitis. These diseases are characterized by airflow blockage and breathing problems. In 2000, the disease was responsible for 119,000 deaths, more than 700,000 hospital admissions, and 1.5 million emergency room visits in the United States.
The main cause of COPD is tobacco use, but asthma, exposure to certain pollutants at home and in the workplace, genetic factors, and respiratory infections may also play a part in the development of the illness. It's believed as many as 10 million adults were diagnosed with COPD in 2000, but a national health survey suggested the numbers could be more than double that.3
According to the American Thoracic Society, the Global Initiative for Obstructive Lung Disease (GOLD) Guidelines recommend long-term use of ICS for people with COPD if tests show their lung function is around half what it should be for someone their age, and if they experience repeated flare-ups. These guidelines are echoed by the American Thoracic Society and the European Respiratory Society.
'Meaningful' Findings About ICSs
In an editorial accompanying the study,4 Jonathan Samet, MD, an epidemiologist at Johns Hopkins Bloomberg School of Public Health, wrote that the risk of death and hospitalization for people with COPD "is particularly crucial" in evaluating the efficacy of inhaled corticosteroids.
However, he said further, even more stringent clinical trials testing the effectiveness of ICSs for COPD are needed.
"Another approach for gaining information is pooling data from individual trials; at the 2005 American Thoracic Society meeting, a reduction in all-cause mortality associated with inhaled corticosteroid therapy was reported, based on 5,082 participants in seven trials," Samet wrote.
In the meantime, the effectiveness of the drugs reported in these latest two studies is definitely "meaningful", he wrote.
1. Kiri VA, Pride NB, Soriano JB, Vestbo J. Inhaled corticosteroids in chronic obstructive pulmonary disease: results from two observational designs free of immortal time bias. Am J Respir Crit Care Med 2005 Aug 15;172(4):460-4. Epub 2005 May 18.
2. Selroos O. The place of inhaled corticosteroids in chronic obstructive pulmonary disease. Curr Med Res Opin 2004 Oct;20(10):1579-93.
3. Centers for Disease Control and Prevention (CDC). Facts About Chronic Obstructive Pulmonary Disease (COPD). Available at: http://www.cdc.gov/nceh/airpollution/copd/copdfaq.htm. Accessed September 1, 2005.
4. Samet JM. Inhaled corticosteroids and chronic obstructive pulmonary disease: new and improved evidence? Am J Respir Crit Care Med 2005 Aug 15;172(4):407-8.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
