Associations between expiratory spirometry parameters and limitations in daily life activities in patients with schizophrenia

Objective: This cross-sectional study considered whether variability in respiratory functioning could explain the variability in walking ability of individuals with schizophrenia taking into account variability in body mass index (BMI), lifestyle factors, psychiatric symptoms, antipsychotic medication use and muscular fitness. Method: Eighty patients with schizophrenia and 40 age-, gender-and BMI-matched controls underwent a spirometry and the 6-min walk test (6MWT) and completed the International Physical Activity Questionnaire. Patients were additionally screened for psychiatric symptoms. Results: Compared to health controls, patients with schizophrenia achieved a lower distance on the 6MWT (583.6 +/- 109.7 m versus 710.6 +/- 108.4 m, P<.001) and had a lower forced vital capacity (3.7 +/- 1.1 L versus 4.3 +/- 0.9 L, P<.001) and forced expiratory volume in 1 s (FEV1) (3.0 +/- 1.0 L versus 3.6 +/- 0.7 L, P<.001). In multiple regression analysis, 68.1% of the variance in walking distance was explained by FEV1, BMI, muscular fitness and total energy expenditure. Conclusion: The respiratory health of patients with schizophrenia should be of concern for clinicians. In addition, future research interventions should seek to investigate the impact of an impaired respiratory health upon individuals with schizophrenia. (C) 2014 Elsevier Inc. All rights reserved.