The Oral Secretion Scale and Prognostic Factors for Survival in Subjects With Amyotrophic Lateral Sclerosis

Noninvasive ventilation (NIV) can be tolerated in patients with amyotrophic lateral sclerosis (ALS), unless bulbar impairment becomes severe. Excessive oral secretions may result in NIV intolerance and insufficient ventilation.

To assess the reliability of the Oral Secretion Scale (OSS) for predicting the tolerance of NIV, when to initiate hospice or transition to tracheostomy, and prognostic factors for survival of users of NIV.

A validated OSS was developed to measure oral secretions in correlation with the ability to swallow saliva and clear the upper airway: OSS score of 4 = normal (automatic swallow); OSS score of 3 = infrequent secretions (automatic swallow decreased); OSS score of 2 = occasional drooling and/or pooling (conscious swallow required); OSS score of 1 = severe, frequent drooling and/or pooling (conscious swallow difficult); OSS score of 0 = most severe, constant drooling/pooling (conscious swallow impossible). A total of 137 subjects were followed up prospectively during ongoing patient visits from NIV initiation until death or tracheostomy. Survival was calculated by using Kaplan-Meier analysis. OSS scores when NIV became intolerable were determined. Uni- and/or multivariate Cox-regression analyses showed prognostic factors that affect survival.

The median months of survival from NIV initiation were the following: 11 (95% CI 7.3-14.0), 5 (95% CI 3.1-6.1), and 1 (95% CI 1.1-1.5) stratified by OSS scores of 4, 3-2, and 1, respectively; and 21 (95% CI 8.6-33.2), 8 (95% CI 3.4-11.5), 6 (95% CI 4.2-8.2), and 2 (95% CI 1.5-2.7) stratified by 24, 17-23, 4-16, and <4 h/d of NIV use, respectively. Survival was significantly (P < .001) longer with an OSS score of 4 than an OSS score of 1 at NIV initiation; and significantly (P < .001) longer when NIV used 24 h/d than <24 h/d. In the subjects unable to tolerate NIV, ≥80% had OSS score of 1 or 0. Univariate and multivariate analyses hazard ratio 4.91, 95% CI 2.98-8.09, P < .001, and hazard ratio 4.60, 95% CI 2.66-7.96, P < .001), respectively, showed hours per day of NIV use was a significant factor associated with survival.

The subjects with an OSS score of 4 tolerated NIV and survived significantly longer than subjects with an OSS score of <4. An OSS score of 1 signaled NIV intolerance and the need for hospice or transition to planned tracheostomy. Use of OSS can help guide NIV management decisions.