Maarten van Egmond

45 The pre- and postoperative course of functional status 3 Maximal inspiratory pressure (MIP) was measured as an indicator of inspiratory muscle strength with a micro-medical spirometer that has been described as valid and reliable. 2,3 Normative values for Caucasian adults were used based on age, sex and height. 22 Fatigue was measured with the multidimensional fatigue inventory (MFI), which is composed of 20 items and organized into five scales: general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue. The MFI has good internal consistency and construct validity. 18,23 ICF: Activities and participation Walking capacity was measured with the 2-minute walk test (2MWT). This test measured the distance a patient was able to walk quickly on a flat, hard surface in a period of 2 minutes. 24,25 The 2MWT correlates highly with the 6-minute walk test, and the intraclass correlation coefficient that indicates the test-retest reliability is 0.82 (95% CI: 0.76 to 0.87). 26 Normative reference values stratified by sex and age were used, as described by Bohannon. 27 Self-reported activities of daily life (ADL) were assessed with the Longitudinal Ageing Study Amsterdam (LASA) Physical Activity Questionnaire (LAPAQ), in which patients reported their activities during the past 14 days. 28 The LAPAQ appears to be valid and reliable for measuring activities in older people. 3,28 Health-related quality of life (HRQL) was measured with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQ-C30), version 3.0. It is a reliable and valid measure of the quality of life of patients with cancer in multicultural clinical research settings. 29 Statistical analysis All data were entered and analysed in the Statistical Package for the Social Sciences (SPSS Inc, Chicago, IL), version 25.0 for Windows. Statistical tests were two-sided and considered significant with an α ≤ .05. Linear mixed model analyses were used to analyse the course of functional status over time and to analyse the differences in course over time between patients with and without postoperative complications.