Marga Hoogendoorn

64 Table 3. Continued NAS activity NAS points per activity Median converted NAS time (minutes) Median observed time, minutes [IQR] Difference in minutes, median [IQR] 22. Specific interventions in the ICU 2.8 NA NA NA 23. Specific interventions outside the ICU 1.9 9.12 18.18 [5.69-27.46] -9.06 [-18.34- 3.43]* 202.56 [155.04-241.2] 98.52 [71.86-127.72] 84.7 [50.31-127.72]* N = 371 patients and 46,319 measured nursing activities. * Indicates a significant P-value of <0.05 (Wilcoxon signed-rank test); NA: not measured during measurement. This is a shortened version of the NAS; the full version can be found on appendix 2 D I SCUSS I ON Our analysis showed that the NAS overestimates the nursing time needed for patients in the Dutch ICU setting. Times of most NAS items were overestimated by the NAS, except for four activities (support or care of patient for about 1 hour, administrative tasks for less than 2 hours, administrative tasks for about 2 hours, and specific interventions outside the ICU), we used in this study to calculate the converted time per NAS point. Using this approximation, the converted time would have changed from 3.84 to 3.62 minutes per NAS point. This change does not affect the results and we therefore conclude that non- nursing duties do not significantly influence the performance of the NAS. A strength of our study is that we validated the NAS with time-and-motionmeasurements, which is considered to be the best technique for measuring nursing workload 13 . To our knowledge, this has not been performed before in the context of NAS validation. Measurements for nursing activities by using time-and-motion measurements are more accurate compared with the work-sampling approach, as used for the development of the NAS 24 . Furthermore, since measurements took place in all types of ICUs, we believe that results of this study are generalizable to all Dutch ICUs. One of the limitations of our study is the fact that we excluded NAS activities because they did not occur or occurred less than ten times. Two of these activities are usually scored in other categories: the activity ‘intravenous replacement of large fluid losses’ is mostly scored under NAS item 1 ‘bedside’. The activity ‘treatment of complicated metabolic acidosis/alkalosis’ is mostly scored in NAS item 3 ‘medication’. Since these activities could be scored in other categories, we did not include them in our study. Three NAS