Maarten van Egmond

33 Preoperative functional status and postoperative complications 2 Third, the type of surgery might also have affected the incidence of postoperative pulmonary complications (Table 1). A majority (77 patients) underwent minimally invasive surgery. This may have led to a lower incidence of postoperative pulmonary complications. 29 However, in our study cohort there was no significant difference in the occurrence of complications between open and minimally invasive surgery. This study has some intrinsic limitations. First, we have only analyzed patients who agreed to have functional status measured and patients who were indicated for surgery only if both their preoperative pulmonary function and general condition was good enough to allow surgery. The selection of relatively healthy patients for surgery, who subsequently had on average a high preoperative functional status, could have resulted in lower discriminative power between functional status and the incidence of POC. Second, a majority of the patients suffered from gastrointestinal complications (32.2 %), which is unlikely to be related to preoperative functional status, where only 18 out of 90 patients suffered from a postoperative pulmonary complication. It could be assumed that the high rate of gastrointestinal complications confounded the overall study conclusion. The sample size within the subgroup of postoperative pulmonary complications was too low to perform a stratified analysis to the association between preoperative functional status and postoperative pulmonary complications without a subsequent risk of a Type 2 error. Third, functional status contains more aspects than we investigated, but we only chose these indicators with good clinical applicability, that have been shown to have an association with POC in other surgical populations. Although aerobic capacity is a risk factor for postoperative outcome, we decided not to include this variable in our study due to the lack of consistency in measuring it. 4 The reason to use a questionnaire to measure PA instead of a more objective measurement tool like an activity monitor was done by means of feasibility. Several questionnaires have been validated to assess PA in older adults, but all showed limitations on psychometric properties and content. 30 First, the LAPAQ is interviewer-administered, which requires training for its application in practice. We solved this by providing in depth training to assessors.