Abstract

Background The Nursing Activities Score (NAS) is widely used for measuring the workload of intensive care unit (ICU) nurses. However, the performance of the NAS to measure actual nursing time has not been comprehensively and externally validated. The aim of this study is to validate the NAS using time-and-motion measurements in Dutch ICUs.
Methods We measured nursing time for patients admitted to seven Dutch ICUs, between November 2016 and October 2017. The patient(s) that were under the care of a chosen nurse were followed by the observers during the entire shift and measurements were performed using an in-house developed web application. To validate the reliability of the NAS, we first converted NAS points per activity into minutes. Next, we compared the converted time per NAS item and the converted total nursing time per patient with the actual observed time. We used Wilcoxon signed-rank tests at nursing activity level and Pearson’s R and R2 at patient level for these comparisons.
Results A Pearson’s correlation of R=0.59 (R2 =0.35) was found between the total converted NAS time and the total observed time per patient. The median converted NAS time per patient (202.6 minutes) was higher compared with the observed time per patient (114.3 minutes). At NAS item level, we found significant differences between the converted NAS time and the observed time for all separate NAS items.
Conclusions The NAS overestimates the nursing time needed for patients in Dutch ICUs. Therefore, we advise revisions of the time weighting assigned to each NAS item to obtain better insight into the true nursing workload so that this information can be used for more effective nursing capacity planning.

Introduction

There are concerns regarding excessively high nursing workload, both in general and ICU wards.[1] An excessively high nursing workload can lead to burnout and job dissatisfaction among nurses[2] and have a deleterious effect on patients.[3] Workload has risen due to an increased turnover of patients, increased complexity of patients, together with nursing shortages.[4] All this makes planning of nursing capacity important. In the last 30 years different instruments have been developed to measure the nursing workload to give insight into the nursing staff needed per shift and provide much needed input for capacity planning.[5] To assess nursing workload in the ICU, Cullen et al.[6] created the Therapeutic Intervention Scoring System (TISS). The TISS was originally developed to classify nursing workload in relation to the severity of illness of ICU patients. The TISS consists of 76 therapeutic interventions that receive 1-4 points based on the severity of illness. It appeared that nursing workload is only partly related to severity of illness, since less severely ill patients could also generate a high nursing workload. For instance, a patient recovering from a serious illness with agitated delirium would not score high in severity of illness, but could demand very intensive nursing care, up to continuous bedside care throughout the day. This made the TISS less effective in assessing nursing workload. Therefore, the Nursing Activities Score (NAS) was developed by Miranda et al. in 2003.[7] The NAS describes activities that largely represent the work actually performed by nurses at the bedside in caring for patients and was developed to measure the nursing workload for each individual patient. The points assigned to nursing activities provide an average time consumption in caring for the patients instead of representing the severity of illness. The NAS was created by using the work-sampling approach: at random moments per shift the nurse was asked what he or she was doing at that specific moment. The researchers applied a weighting for each activity. The total NAS for an individual patient is the sum of NAS points for all activities, varying between 0 to 177 points. A score of 100 NAS points is equivalent to the amount of care that can be provided by one full-time equivalent nurse during either one shift or one day. A score above 100 points indicates that the care needed can only be provided by more than one nurse.[7] The NAS is considered a valuable tool and is widely used for workload measurement in ICUs.[8,9] However, the performance of the NAS has not been comprehensively validated. One study showed that the NAS might either underestimate or overestimate the actual nursing time required by patients and therefore recommended revision of the original NAS because of inadequate measurement of nursing activities.[4] The study by Stafseth et al. suggests that the reliability and validity of the NAS are good. However, this study strongly suggests more research in other countries and larger groups of patients.[10]

Furthermore, research has demonstrated that the worksampling approach, as used for the development of the NAS, does not lead to an accurate representation of the true nursing workload. This is due to the fact that the weighting of nursing activities is based on the probability that a particular nursing activity occurred.[11] The total amount of time in a shift is divided over the nursing activities that were carried out. When nursing activities frequently occur or take a lot of time, they would also occur more frequently in the work-sampling approach. However, this approach will not lead to precise measurements, but will only approximate the time of the different activities. Thus, in contrast to time-and-motion techniques in which every minute of a nursing shift is measured, the work-sampling approach does not measure the real amount of time spent on nursing activities, which could lead to less accurate results.[12] Therefore, the time-and-motion technique is considered the best technique for time measurement.[13] The aim of this study is to validate the NAS in the Dutch ICU setting using the time-and-motion technique, and to identify which nursing activities are underestimated or overestimated in the NAS.

Methods

Setting
We conducted an observational study. All 82 Dutch ICUs participate in the National Intensive Care Evaluation (NICE) quality registry. Fifteen of these ICUs are participating in the newly implemented voluntary nursing capacity module[14], seven of which voluntarily took part in this study. Data on characteristics of the ICUs (such as number of ICU beds) and data on patient characteristics (such as age, BMI, admission type, and mortality) were extracted from the NICE registry.

Time-and-motion
The study involved time-and-motion measurements for patients admitted to the ICU. We included different types of hospitals (academic, teaching and non-teaching hospitals) and different shifts (day, evening and night). We performed an equal number of measurements in all types of hospitals and shifts. At the start of a shift, one nurse was chosen by the observer. The patient(s) that were under the responsibility of this nurse were followed by the observer during the entire shift. A longer-term patient could theoretically be observed on different dates during different shifts and therefore could possibly be followed during more than one measured shift. The measurements took place on different days of ICU admission (e.g. first ICU admission day through to last ICU admission day) and with different types of nurses (registered and student nurses). We randomly selected nurses who took care of patients that were expected to stay during the whole shift in order to measure as many nursing activities as possible. Observers were researchers CM and MH and ten student nurses. The students were trained in performing time-and-motion measurements by oral and written instructions and one day of measuring together with one of the researchers. The observers used an in-house developed web application to record start and stop times of each performed nursing activity. The application included all activities occurring in the NAS (table 1). If two nurses were simultaneously performing nursing activities for the same patient, this was also registered by pressing the ‘two nurses button’ and multiplying this time by two in the analysis. When two different activities were carried out by two nurses, these activities could be measured simultaneously. Measurements were conducted between 1 November 2016 and 1 October 2017. Participation of the hospitals was on a voluntary basis. Seven hospitals were willing to participate. Data were processed anonymously.

Ethical approval
The Institutional Research Board of the Amsterdam University Medical Centre reviewed the research proposal and waived the need for informed consent (IRB protocol W17_366).

Data analysis
Nursing activities that occurred less than ten times in the total dataset were excluded from the analysis. Most NAS items have a fixed number of NAS points but some items have different categories corresponding to different numbers of NAS points depending on the duration of that activity (e.g. bedside with hourly vital signs, bedside for two hours or more, or four hours or more). For these duration-dependent activities, we first used the measured time for that activity to assign the correct number of points. For example, a nurse performed hygiene procedures on a patient for 1.2 hours during a shift, according to our time measurements. This NAS item has three categories: performing hygiene procedures for less than two hours, for more than two hours, or for more than four hours.

Table 1. NAS activities with their points according to Miranda et al. (2003),[7] and the median converted NAS times and observed times per NAS item