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The prognostic value of exercise testing in patients with cystic fibrosis.

Abstract

BACKGROUND

Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and colonization of the respiratory tract with Pseudomonas cepacia to be associated with a poor prognosis in patients with cystic fibrosis. We sought to determine the prognostic value of exercise testing in addition to the other prognostic factors.

METHODS

A total of 109 patients with cystic fibrosis, 7 to 35 years old, underwent pulmonary-function and exercise testing in the late 1970s. They were followed for eight years to determine the factors associated with subsequent mortality. Survival rates were calculated with standard life-table methods. Cox proportional-hazards regression models were used to determine crude relative risks of mortality and relative risks adjusted for age, sex, body-mass index, forced expiratory volume in one second (FEV1) end-tidal partial pressure of carbon dioxide (PCO2) at peak exercise, and oxygen consumption at peak exercise (VO2 peak).

RESULTS

Patients with the highest levels of aerobic fitness (VO2 peak, > or = 82 percent of predicted) had a survival rate of 83 percent at eight years, as compared with rates of 51 percent and 28 percent for patients with middle (VO2 peak, 59 to 81 percent of predicted) and lowest (VO2 peak, < or = 58 percent of predicted) levels of fitness, respectively. After adjustment for other risk factors, patients with higher levels of aerobic fitness were more than three times as likely to survive than patients with lower levels of fitness. Colonization with P. cepacia was associated with a risk of dying that was increased fivefold. Age, sex, body-mass index, FEV1, and end-tidal PCO2 at peak exercise were not independently correlated with mortality.

CONCLUSIONS

Higher levels of aerobic fitness in patients with cystic fibrosis are associated with a significantly lower risk of dying. Although better aerobic fitness may simply be a marker for less severe illness, measurement of VO2 peak appears to be valuable for predicting prognosis. Further research is warranted to determine whether improving aerobic fitness through exercise programs will result in a better prognosis.

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  • Authors+Show Affiliations

    ,

    Department of Pediatrics, University of Pittsburgh, PA.

    , ,

    Source

    The New England journal of medicine 327:25 1992 Dec 17 pg 1785-8

    MeSH

    Adolescent
    Adult
    Child
    Cystic Fibrosis
    Exercise Test
    Female
    Humans
    Male
    Physical Fitness
    Prognosis
    Proportional Hazards Models
    Respiratory Function Tests
    Survival Rate

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't
    Research Support, U.S. Gov't, P.H.S.

    Language

    eng

    PubMed ID

    1435933

    Citation

    Nixon, P A., et al. "The Prognostic Value of Exercise Testing in Patients With Cystic Fibrosis." The New England Journal of Medicine, vol. 327, no. 25, 1992, pp. 1785-8.
    Nixon PA, Orenstein DM, Kelsey SF, et al. The prognostic value of exercise testing in patients with cystic fibrosis. N Engl J Med. 1992;327(25):1785-8.
    Nixon, P. A., Orenstein, D. M., Kelsey, S. F., & Doershuk, C. F. (1992). The prognostic value of exercise testing in patients with cystic fibrosis. The New England Journal of Medicine, 327(25), pp. 1785-8.
    Nixon PA, et al. The Prognostic Value of Exercise Testing in Patients With Cystic Fibrosis. N Engl J Med. 1992 Dec 17;327(25):1785-8. PubMed PMID: 1435933.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - The prognostic value of exercise testing in patients with cystic fibrosis. AU - Nixon,P A, AU - Orenstein,D M, AU - Kelsey,S F, AU - Doershuk,C F, PY - 1992/12/17/pubmed PY - 1992/12/17/medline PY - 1992/12/17/entrez SP - 1785 EP - 8 JF - The New England journal of medicine JO - N. Engl. J. Med. VL - 327 IS - 25 N2 - BACKGROUND: Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and colonization of the respiratory tract with Pseudomonas cepacia to be associated with a poor prognosis in patients with cystic fibrosis. We sought to determine the prognostic value of exercise testing in addition to the other prognostic factors. METHODS: A total of 109 patients with cystic fibrosis, 7 to 35 years old, underwent pulmonary-function and exercise testing in the late 1970s. They were followed for eight years to determine the factors associated with subsequent mortality. Survival rates were calculated with standard life-table methods. Cox proportional-hazards regression models were used to determine crude relative risks of mortality and relative risks adjusted for age, sex, body-mass index, forced expiratory volume in one second (FEV1) end-tidal partial pressure of carbon dioxide (PCO2) at peak exercise, and oxygen consumption at peak exercise (VO2 peak). RESULTS: Patients with the highest levels of aerobic fitness (VO2 peak, > or = 82 percent of predicted) had a survival rate of 83 percent at eight years, as compared with rates of 51 percent and 28 percent for patients with middle (VO2 peak, 59 to 81 percent of predicted) and lowest (VO2 peak, < or = 58 percent of predicted) levels of fitness, respectively. After adjustment for other risk factors, patients with higher levels of aerobic fitness were more than three times as likely to survive than patients with lower levels of fitness. Colonization with P. cepacia was associated with a risk of dying that was increased fivefold. Age, sex, body-mass index, FEV1, and end-tidal PCO2 at peak exercise were not independently correlated with mortality. CONCLUSIONS: Higher levels of aerobic fitness in patients with cystic fibrosis are associated with a significantly lower risk of dying. Although better aerobic fitness may simply be a marker for less severe illness, measurement of VO2 peak appears to be valuable for predicting prognosis. Further research is warranted to determine whether improving aerobic fitness through exercise programs will result in a better prognosis. SN - 0028-4793 UR - https://www.unboundmedicine.com/medline/citation/1435933/The_prognostic_value_of_exercise_testing_in_patients_with_cystic_fibrosis_ L2 - https://www.nejm.org/doi/10.1056/NEJM199212173272504?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=www.ncbi.nlm.nih.gov DB - PRIME DP - Unbound Medicine ER -