High-Resolution CT Screening for Lymphangioleiomyomatosis in Women with Collapsed Lung is Cost-Effective

Pulmonary LAM is a rare but serious lung disease that occurs when smooth muscle tissue proliferates within the interstitium of the lung in the form of characteristic thin-walled lung cysts. Many patients present with shortness of breath, which is often misdiagnosed as asthma. But about one-third of LAM patients develop a spontaneous pneumothorax, or a collapsed lung, as the first major sign. But because of its rarity, LAM is rarely diagnosed immediately.

"Women with LAM who first experience spontaneous lung collapse will, on average, experience two more, but diagnosis doesn't usually occur until the second or third collapse, delaying treatment,” said Brent Kinder, M.D., assistant professor of medicine and director of the University of Cincinnati (OH, USA) Interstitial Lung Disease Center and an investigator in the study. "We thought that targeting screening to nonsmoking women in the age range of typical LAM development may help us identify the condition earlier and improve quality of life for these patients.”

Dr. Kinder and Jared Hagaman, M.D., clinical research fellow in pulmonary, critical care and sleep medicine, along with other University of Cincinnati colleagues in the department of medicine, developed a model to evaluate the cost-effectiveness of screening patients for LAM. Using U.S. representative data sources, researchers looked at rates of collapsed lung and prevalence of LAM in relation to age, gender, and smoking status. They compared the benefit and cost of using high-resolution CT screening following lung collapse for patients with LAM to no CT screening. Costs of testing and treatment were taken from 2007 Medicare data.

Approximately 5% of women who fit the "model patient” profile--a 30-year old, nonsmoking woman who comes into the emergency room with a spontaneous lung collapse--test positive for LAM. "Screening for LAM using a high-resolution CT, or three-dimensional X-ray of the lungs, is the most cost-effective strategy, with approximately [US]$32,000 per quality-adjusted life year gained,” said Dr. Kinder. "For comparison, hemodialysis, a standard benchmark for cost-effectiveness, costs about $50,000 per quality-adjusted life year gained. With this data, physicians will be able to intervene with therapies more quickly and enroll patients in clinical trials that may be able to slow progression of the disease.”

Furthermore, Dr. Kinder pointed out, HRCT screening adds a low amount of risk to the LAM-negative population with respect to added radiation. "We believe the benefits of testing outweigh any negative impact on patients without LAM. Additionally, there will be benefits of high-resolution CT scanning for those with diagnoses of lung diseases other than LAM [such as Langerhans cell histocytosis, lymphocytic interstitial pneumonitis, and others]. The radiation dose of high-resolution CT scans is approximately one-tenth that of conventional CT scans, and with newer technology the radiation exposure continues to decrease.”

Due to the sudden nature of pneumothoraces, and their relative rarity, a prospective study in this population is not practicable. But the current findings may have immediate bearing on current clinical practices. "We believe that this study is a useful example of the utility of modern decision analysis techniques to answer important questions in comparative effectiveness research. We believe that this study may change current best practices; particularly if we are successful in raising awareness among emergency room providers, who typically manage these subjects during their acute sentinel event,” said Dr. Kinder.

John Heffner, M.D., past president of the ATS believes that the study will change future guideline recommendations in how to treat patients presenting with pneumothorax. "According to this study, only 20 women presenting with an initial pneumothorax would need to be screened by high-resolution CT to identify one patient with LAM,” he said. "Early detection not only provides opportunities for prevention of subsequent pneumothoraces, but also allows patient counseling, family planning, lifestyle adjustments, and early enrollment in clinical trials that are investigating innovative therapies for what is now an untreatable and progressive disorder. The results from the study will inform clinical approaches for the management of patients with pneumothorax in the future. Clearly, not all patients or even all women who present with an initial pneumothorax should undergo HRCT scanning, but I believe that the impressive cost effectiveness demonstrated in this investigation will encourage future patients' guideline developers to recommend CT scanning for all nonsmoking woman between the ages of 25-54 years.”

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