Scoring Dysphagia Severity
The Dysphagia Outcome and Severity Scale (DOSS) is the best validated method for scoring dysphagia severity, providing a systematic 7-point scale with high inter-rater reliability (90%) and intra-rater reliability (93%) that directly links severity ratings to functional recommendations for diet level, independence, and nutrition. 1
Primary Recommended Scoring System
Use the DOSS as your primary severity scoring tool because it systematically rates functional severity based on three critical assessment areas: oral stage bolus transfer, pharyngeal stage retention, and airway protection. 1 The scale ranges from Level 7 (normal in all situations) to Level 1 (severe dysphagia, nothing by mouth), with each level providing specific recommendations for diet consistency, supervision requirements, and nutritional support. 1
The DOSS demonstrates strong criterion validity when used with both videofluoroscopy (VFSS) and flexible endoscopic evaluation of swallowing (FEES), with correlation coefficients of rs = 0.936 for DOSS-to-DOSS comparison and rs = 0.858 for DOSS-to-FOIS comparison. 2 This makes it applicable regardless of which instrumental assessment you perform.
Alternative Validated Scales
Functional Outcome Swallowing Scale (FOSS)
The FOSS provides a simpler 6-stage system (Stage 0 through Stage V) that emphasizes functional outcomes and nutritional impact. 3 Use FOSS when you need to track weight loss and aspiration complications over time, as it specifically incorporates:
- Stage III: Weight loss ≤10% over 6 months or daily aspiration during meals 3
- Stage IV: Weight loss >10% over 6 months or severe aspiration with bronchopulmonary complications 3
- Stage V: Nonoral feeding for all nutrition 3
Dysphagia Severity Scale (DSS)
The DSS focuses specifically on videofluoroscopic findings, rating penetration/aspiration (P/A) and pharyngeal retention (PR) separately, then combining them by taking the higher score. 4 This scale correlates well with clinical severity ratings (r = 0.71) and is particularly useful when you need to distinguish between aspiration of different consistencies (thin liquids versus thick liquids/solids). 4
Disease-Specific Considerations
ALS Patients
For ALS patients, incorporate the ALS Functional Rating Scale-Revised (ALSFRS-R) or ALS Swallowing Severity Scale (ALSSS) alongside DOSS, as these disease-specific scales capture progression of bulbar symptoms and correlate with nutritional decline. 5 Screen every 3 months given the median survival of 18-28 months and high risk of aspiration pneumonia (13-15% prevalence). 5
Multiple Sclerosis Patients
In MS patients, use the DYMUS (Dysphagia in Multiple Sclerosis) questionnaire for initial screening, which identifies 92% of symptomatic patients and 14% of asymptomatic patients requiring further evaluation. 5 Follow positive screens with instrumental assessment using DOSS scoring, particularly in patients with cerebellar dysfunction, severe disability (high EDSS scores), or long disease duration. 5
Critical Implementation Factors
Experience and Training Requirements
Ensure raters have >3 years of VFSS experience before relying on DOSS scores for clinical decision-making, as inter-rater reliability is significantly higher in experienced clinicians (κ = 0.342) compared to those with <3 years experience (κ = 0.298). 6
Always include audio recording during VFSS when using DOSS, as reliability drops dramatically without audio (κ = 0.287 with audio versus κ = -0.0395 without audio). 6 The audio component allows assessment of wet vocal quality and cough effectiveness, which are critical for accurate severity rating.
Common Pitfalls to Avoid
Never rely on bedside clinical examination alone to assign severity scores, as 55% of patients who aspirate have silent aspiration without protective cough reflex. 7 Always confirm with instrumental assessment (VFSS or FEES). 8, 9
Do not assume training improves DOSS reliability—paradoxically, one study found inter-rater reliability decreased post-training (κ = 0.218) compared to pre-training (κ = 0.328). 6 This suggests standardized clinical experience matters more than brief training sessions.
Avoid using modified barium swallow alone without complete esophageal evaluation, as the American College of Radiology emphasizes that combining videofluoroscopy with biphasic esophagram provides higher diagnostic yield and prevents missing distal pathology causing referred pharyngeal symptoms. 8, 9
Linking Severity to Nutritional Outcomes
Document BMI and weight loss percentage alongside your severity score, as malnutrition prevalence ranges from 0-21% at diagnosis to 7.5-53% during follow-up in neurological dysphagia. 8 Weight loss >10% indicates malnutrition in 21-48% of dysphagic patients and should trigger consideration of enteral nutrition regardless of the specific DOSS level. 8