Reduced peak oxygen uptake and implications for cardiovascular health and quality of life in patients with schizophrenia

Background: Peak oxygen uptake (VO2peak) is a strong predictor of cardiovascular disease (CVD) and all-cause mortality, but is inadequately described in patients with schizophrenia. The aim of this study was to evaluate treadmill VO2peak, CVD risk factors and quality of life (QOL) in patients with schizophrenia (ICD-10, F20-29). Methods: 33 patients, 22 men (33.7 +/- 10.4 years) and 11 women (35.9 +/- 11.5 years), were included. Patients VO2peak were compared with normative VO2peak in healthy individuals from the Nord-Trondelag Health Study (HUNT). Risk factors were compared above and below the VO2peak thresholds; 44.2 and 35.1 ml.kg(-1).min(-1) in men and women, respectively. Results: VO2peak was 37.1 +/- 9.2 ml . kg(-1).min(-1) in men with schizophrenia; 74 +/- 19% of normative healthy men (p < 0.001). VO2peak was 35.6 +/- 10.7 ml.kg(-1).min(-1) in women with schizophrenia; 89 +/- 25% of normative healthy women (n.s.). Based on odds ratio patients were 28.3 (95% CI = 1.6-505.6) times more likely to have one or more CVD risk factors if they were below the VO2peak thresholds. VO2peak correlated with the SF-36 physical functioning (r = 0.58), general health (r = 0.53), vitality (r = 0.47), social function (r = 0.41) and physical component score (r = 0.51). Conclusion: Men with schizophrenia have lower VO2peak than the general population. Patients with the lowest VO2peak have higher odds of having one or more risk factors for cardiovascular disease. VO2peak should be regarded as least as important as the conventional risk factors for CVD and evaluation of VO2peak should be incorporated in clinical practice.