A standard operating procedure for King's ALS clinical staging

Abstract

Objective: Clinical stages in amyotrophic lateral sclerosis (ALS) can be measured using a simple system based on the number of CNS regions involved and requirement for gastrostomy or noninvasive ventilation (NIV). We aimed to design a standard operating procedure (SOP) to define the standardized use and application of the King's staging system. Methods: We designed a SOP for the King's staging system. We wrote case vignettes representative of ALS patients at different disease stages. During two workshops, we taught health care professionals how to use the SOP, then asked them to stage the vignettes using the SOP. We measured the extent to which SOP staging corresponded with correct clinical stage. Results: The reliability of staging using the SOP was excellent, with a Spearman's Rank coefficient of 0.95 (p < 0.001), and was high for different groups of health care professionals, and for those with different levels of experience in ALS. The limits of agreement between SOP staging and actual clinical stage lie within a single stage, confirming that there is a clinically acceptable level of agreement between staging using the SOP and actual King's clinical stage. There were also no systematic biases of the SOP over the range of stages, either for over-staging or under-staging. Conclusions: We have demonstrated that the staging SOP provides a reliable method of calculating clinical stages in ALS patients and can be used prospectively by a range of health care professionals with different levels of experience, as for example may be the case in multicentre clinical trials.

Keywords: Clinical trials; prognostic, staging,  standard operating procedure; survival.

Figure 1

Demographics of participants included in the study. (A) The study consisted of 61 participants in total, with doctors (65.5%), nurses (9.1%), and allied health care professionals (25.5%) represented in the cohort. (B) There was an even distribution between those with less than 10 years’ experience working in ALS (50.8%) and those with 10 years’ or greater experience (48.2%).

Figure 2

Use of a standard operating procedure leads to reliable clinical staging. Participants were trained in how to use the staging standard operating procedure (SOP, Supplementary Material), and most correctly staged case vignettes using the SOP. The numbers to the right of each bubble represent the number of answers within each group.

Figure 3

Variability of scores for staging using the SOP for each case vignette. Bars represent the mean and standard deviation of scores for staging using the SOP for each vignette. Variability in the answers was greatest for vignettes 8, 9, and 12.