# Limit values for the web instrument Need for Recovery based on health over two years and corresponding psychosocial working environment

## TL;DR

This study establishes a health-based limit for work-related fatigue to monitor workers' health and psychosocial work environment over two years.

## Contribution

The novel contribution is deriving a specific Need for Recovery (NFR) limit value (9/33) to predict long-term health impacts and psychosocial work conditions.

## Key findings

- A baseline NFR score of 9.02 predicted health impacts two years later.
- The healthy NFR limit was set at 9/33 with 85% sensitivity and 74% specificity.
- Work process resources and work demands were key psychosocial factors linked to health.

## Abstract

The magnitude of fatigue or need for recovery (NFR) from work shifts could be used as a tool for health surveillance and for monitoring rehabilitation.

To develop a model to calculate the healthy limit value for NFR based on health over two years in a cohort of workers and from there healthy limit values for the psychosocial work environment. The model is to be used in a web instrument.

Based on survey data from 1289 engineers, carpenters, nurses and home care employees, NFR was calibrated against six Copenhagen Psychosocial Questionnaire (COPSOQ II) health scales. Regression models explored the correspondence between NFR at baseline and regularity in function impact on health over two years. Thereafter, the limit values for the psychosocial work environment were examined. Successive calculations concerned sensitivity and specificity of these limit values.

The baseline NFR value that predicted a set minimum level of regularity of impact on health from each health scale two years later (p < 0.001), formed a mean minimum of regularity NFR score of = 9.02. The limit healthy NFR value was set below this value to 9/33 points. Sensitivity regarding the limit healthy NFR value concerning prediction of an unhealthy NFR was 85%. Specificity regarding healthy cases was 74%. Healthy limit values for the psychosocial work environment concerned first of all work process resources and then work demands.

A Need for Recovery limit value could be based on the frequency of the fatigue reaction and function impact on health (frequency).