Instruments to assess moral distress among healthcare workers : A systematic review of measurement properties

Background
An increasing number of professionals is challenged by the evolution of modern healthcare and society, often characterized by more expectations with reduced resources. Moral distress is among the psychophysical conditions now most under investigation in order to improve the wellbeing of professionals, the sustainability of organizations and the quality of care. Over the last decades, several instruments have been developed to assess the frequency or intensity of moral distress in different studies. Yet, there has not been, so far, a systematic assessment of the qualitative properties of the various instruments measuring moral distress in healthcare workers based on a universally accepted standardized framework.

Objective
(1) To identify all instruments for the measurement of moral distress available in recent literature; (2) to evaluate the evidence regarding their measurement properties; (3) to facilitate the selection of the most appropriate instrument to be adopted in practice and research.

Design
Systematic literature review.

Data sources
PubMed, CINAHL, and PyscINFO.

Review methods
The COnsensus-based Standards for the selection of health Measurement INstruments checklist was used to evaluate the methodological quality of the identified studies. The quality of measurement properties of each instrument was evaluated using Terwee's quality criteria.

Results
Among the 1268 studies found, 88 full-text articles evaluated moral distress adopting different tools. 32 of them had a methodological design. The measurement instruments assessed in this review are different in terms of targeted population and items. The instruments were then divided into two main categories: (1) Corley's instruments on moral distress (Moral distress scale and Moral Distress Scale – Revised) and (2) instruments not directly derived from Corley's moral distress theory (Moral Distress thermometer, Moral Distress Risk Scale, Ethical Stress Scale or Moral Distress in Dementia Care Survey). The first set is the most frequently studied and used in different clinical settings and healthcare populations. A variety of psychometric properties have been evaluated for each instrument, revealing different qualities in the methodology used.

Conclusions
Several instruments assessing moral distress in healthcare workers have been identified and evaluated in this systematic review. Based on the criteria used here, Corley's instruments on moral distress seems to be the most useful and most appropriate to the clinical setting for practice and research purposes.

Tweetable abstract
The aim of this systematic review was to identify the instruments measuring moral distress now available in the literature, in order to (1) assess the evidence about their measurement properties, (2) support the selection of the most appropriate instrument to be used in practice and research.