Associations between expiratory spirometry parameters and limitations in daily life activities in patients with schizophrenia Davy Vancampfort, Ph.D. a, b, ⁎, Michel Probst, Ph.D. a, b , Brendon Stubbs, M.Sc. c , Andrew Soundy, Ph.D. d , Amber De Herdt, M.Sc. b , Marc De Hert, Ph.D., M.D. b a University Psychiatric Centre KU Leuven, Kortenberg, KU Leuven Departement of Neurosciences, B-3070Kortenberg, Belgium b KU Leuven Department of Rehabilitation Sciences, B-3001Leuven, Belgium c School of Health and Social Care, University of Greenwich,Eltham, LondonSE9 2UG, UK d Department of Physiotherapy, University of Birmingham, Birmingham, B15 2TT, UK abstract article info Article history: Received 23 July 2013 Revised 31 October 2013 Accepted 4 November 2013 Keywords: Walking Physical activity Spirometry 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, Pb .001) and had a lower forced vital capacity (3.7±1.1 L versus 4.3± 0.9 L, Pb .001) and forced expiratory volume in 1 s (FEV1) (3.0±1.0 L versus 3.6±0.7 L, Pb .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. © 2014 Elsevier Inc. All rights reserved. 1. Introduction Patients with schizophrenia are known to be impaired in their ability to perform daily life activities such as walking. For example, patients with schizophrenia walk up to 20% less distance on the 6-min walk test (6MWT) compared with healthy controls (Pb .001, effect size=-1.01) [1]. Previous research has demonstrated that this impaired walking performance is associated with overweight and metabolic complications [2], an impaired muscular fitness [1], smoking behavior [1], negative and depressive symptoms [3], antipsychotic medication use [3] and a lower physical self-perception [4]. Importantly, the impaired ability to walk is also related to a reduced health-related quality of life [5] and impairments in global social and emotional functioning [6]. For these reasons, it is important to investigate factors that contribute to this reduced ability to perform daily life activities since clearly this has important implications for clinical practice. One factor that may contribute to the reduced level of walking and functioning is an impaired lung function. Previous studies in patients with systemic sclerosis [7], pulmonary sarcoidosis [8] and bronchi- ectasis [9] demonstrated that expiratory lung function parameters are associated with scores obtained on functional walk tests. To the best of our knowledge, the association between walking and expiratory lung function parameters has not yet been explored in patients with schizophrenia. This is surprising since several epidemiological studies [10–12] have reported on the association between an impaired lung function and increased morbidity and mortality in patients with schizophrenia. In addition, patients with severe mental illnesses have a reduced forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) compared to healthy controls [10]. Impairments in these lung function parameters are also associated with metabolic complications [13]. The first aim of this study was to quantify FEV1 and FVC in patients with schizophrenia compared with age-, gender- and body mass index (BMI)-matched healthy controls. Secondly, in order to inves- tigate whether expiratory lung function parameters are associated with the ability to walk, a second aim of this cross-sectional study was to identify whether, in patients with schizophrenia, the variability in expiratory lung function parameters could explain the variability in walking ability taking into account gender, variability in BMI, lifestyle General Hospital Psychiatry 36 (2014) 172–176 ⁎ Corresponding author. University Psychiatric Centre KU Leuven, Campus Kortenberg. Leuvensesteenweg 517, B-3070 Kortenberg, Belgium. Tel.: +32 2 758 05 11; fax: +32 2 759 9879. E-mail address: Davy.Vancampfort@uc-kortenberg.be (D. Vancampfort). 0163-8343/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.genhosppsych.2013.11.001 Contents lists available at ScienceDirect General Hospital Psychiatry journal homepage: http://www.ghpjournal.com