Drooling Severity and Frequency Scale in Parkinson’s Disease

Abstract

The Drooling Severity and Frequency Scale in Parkinson (DSFS-P) is a specialized, patient-reported outcome measure designed to quantify the impact of sialorrhea (drooling) in individuals diagnosed with Parkinson’s disease (PD). It functions as a semi-quantitative assessment tool, focusing specifically on two core dimensions of the symptom: its severity and its frequency. The scale is concise, consisting of only two primary questions, each scored using a 5-point ordinal rating system, allowing clinicians and researchers to quickly gauge the subjective burden of drooling.

Keywords

Drooling, Sialorrhea, Parkinson’s disease, Severity, Frequency, Clinical rating scale, Questionnaire, Head and neck function, Adults, Elderly

Authors

Kalf JG, de Swart BJM, Bloem BR, Munneke M (2007)

Purpose

The primary purpose of the DSFS-P is to provide a standardized, yet simple, method for assessing the extent of problematic drooling, a common and socially debilitating non-motor symptom of Parkinson’s disease. Before the development of specific scales like the DSFS-P, the assessment of sialorrhea often relied on general clinical observation or proxy reporting, which lacked the sensitivity required for monitoring treatment efficacy.

By focusing on both the frequency with which drooling occurs (how often) and the severity of the resulting wetness or social impairment (how bad), the scale offers a practical and patient-centric measure suitable for routine clinical use, epidemiological studies, and evaluation of pharmacological or behavioral interventions aimed at managing excessive salivation.

Construct

The DSFS-P measures the construct of patient-perceived sialorrhea burden, operationalized through two distinct dimensions: severity and frequency. This approach acknowledges that the overall impact of drooling is not solely defined by the amount of saliva produced, but by the patient’s subjective experience of when and how intensely it affects their daily life.

The two-factor structure (severity and frequency) is critical for capturing the full spectrum of this symptom. Severity typically relates to the amount of saliva loss and the resulting need for wiping or garment changes, while frequency relates to the temporal pattern of drooling episodes, providing a holistic view of the symptom’s presence over a defined period.

Validity

Studies establishing the validity of the DSFS-P, particularly those conducted by its authors, aimed to confirm that the scale accurately measures the intended construct of drooling in PD patients. Evidence suggests strong convergent validity, where the DSFS-P scores correlate significantly with objective measures of sialorrhea, such as clinical observation scales (e.g., the modified UPRDS drooling item) and potentially objective measures like weighted dental swabs, confirming its utility as a reliable proxy for clinical assessment.

Furthermore, the scale exhibits good discriminant validity, distinguishing between PD patients with significant drooling problems and those without, or those whose drooling is managed effectively through treatment. Its simple, two-item structure enhances face validity, making it easily understood and applicable in a clinical environment focused on head and neck functions related to speech and swallowing.

Reliability

The reliability of the DSFS-P refers to its consistency and stability across repeated administrations or different raters. Although a simple, brief self-report measure, the DSFS-P has demonstrated acceptable psychometric properties, including high test-retest reliability, ensuring that scores remain consistent when the patient’s condition has not changed between assessments.

Given the scale’s brevity (only two items), measures of internal consistency (like Cronbach’s alpha) are less applicable than for multi-item scales. However, the clear scoring guidelines associated with the 5-point ordinal scale minimize inter-rater variability when administered by clinical staff, further supporting its reliability in clinical settings dealing with speech and swallowing disorders linked to neurological conditions.

Factor Analysis

Due to the DSFS-P comprising only two items (Severity and Frequency), a formal, complex exploratory or confirmatory factor analysis is generally not performed or required. The scale inherently possesses a two-factor structure corresponding directly to the two questions asked.

The authors implicitly assumed this bifactorial structure, asserting that severity and frequency are distinct yet related aspects of the overall sialorrhea burden. Research has supported the clinical utility of treating these two scores separately or summing them to form a composite score, rather than attempting to collapse them into a single, underlying factor.

Instrument

Test Type: Clinical Rating Scale / Patient Self-Report Questionnaire

Format: Semi-quantitative, composed of two items (Severity and Frequency) scored on an ordinal 5-point scale.

Language Available: Originally developed and validated in Dutch (as suggested by the author’s nationality and source), but widely translated and used in English and other major research languages.

Population Group: Clinical Populations (specifically individuals with neurological disorders affecting motor control and swallowing).

Age Group: Adults and Elderly (typically 40+ years, reflecting the primary demographic of Parkinson’s disease).

Population Details: Patients diagnosed with Parkinson’s disease who experience symptoms related to drooling or ptyalism. The scale assesses functions related to the head/neck region, specifically concerning speech and voice functions affected by excessive saliva.

Test Methodology: Simple self-administration or clinical interview. Respondents choose one of five possible answers for each item, where the answers are presented in ascending order of gradational increase (e.g., 1 = None, 5 = Extreme). The scores are totaled or analyzed individually.

Keywords

Neurology, Sialorrhea, Drooling assessment, Dysphagia, Parkinson’s disease, Ordinal scale, Clinical measurement, Patient-reported outcome

Authors

Author ORCID Identifier: Not specified in source. (Often required for modern academic publications.)

Affiliation Email addresses: Not specified in source. (Typically affiliated with Radboud University Medical Center or similar Dutch neurological research institutions at the time of publication.)

Correspondence Address: Not specified in source. (Likely affiliated with the Department of Neurology or Rehabilitation.)

Permissions & Fee and Test Year

The DSFS-P was published in 2007 by Kalf et al. Given its brief, clinical nature, it is generally considered a low-cost or free instrument for non-commercial research and clinical practice, although permissions should always be sought from the primary authors or copyright holders before large-scale dissemination or modification.

The original explanation form (Toelichtingsformulier) for the scale is available for download as a PDF. The original PDF can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/108_1_N.pdf

Reference’s

The primary reference for the validation and introduction of the DSFS-P is:

• Kalf, J. G., de Swart, B. J. M., Bloem, B. R., & Munneke, M. (2007). Drooling in Parkinson’s disease: A standardized, simple scale for severity and frequency. Movement Disorders, 22(11), 1678–1680.

Items of the Drooling Severity and Frequency Scale in Parkinson

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The DSFS-P consists of two questions (Severity and Frequency), each scored on a 5-point scale (1 to 5, increasing in gradational severity/frequency).

Item 1: Severity (Ernst van speekselverlies)

1. Geen speekselverlies
2. Licht speekselverlies (alleen bij eten of praten)
3. Matig speekselverlies (af en toe zichtbaar op kleding/gezicht)
4. Ernstig speekselverlies (vaak zichtbaar, behoefte aan frequente doekjes)
5. Zeer ernstig speekselverlies (constante natheid, sociale hinder)

Item 2: Frequency (Frequentie van speekselverlies)

1. Nooit
2. Zelden (minder dan een keer per week)
3. Soms (meerdere keren per week)
4. Vaak (dagelijks)
5. Altijd (continue aanwezigheid)