Dry mouth in patients with a life-limiting condition or frailty: a study protocol for two intervention studies and a nested qualitative sub-study (the Dry mOuth Project, DROP)

BACKGROUND: Despite its prevalent and impactful nature, dry mouth remains an underexposed and undertreated symptom in patients with a life-limiting condition or frailty. The main contributing factors are a lack of awareness and knowledge amongst both healthcare professionals and patients, and a scarcity of effective, evidence-based interventions. In the DRy mOuth Project (DROP), we address these factors by investigating both a non-pharmacological and a pharmacological intervention: a nurse-led patient education program and locally applied pilocarpine. METHODS: This intervention-based research project consists of two parallel studies. The non-pharmacological study is a cluster non-randomized controlled trial in 228 palliative nursing home and hospital patients, investigating the effect of structured use of guidelines and of patient education on dry mouth symptoms. This intervention, a nurse-led patient education program (the Mouth Education Program, MEP), will be compared to care as usual, the control. The pharmacological study is a double-blind placebo-controlled randomized trial that examines the effect of locally applied pilocarpine drops in 120 patients with dry mouth symptoms. Both studies use the same mixed-methods study design, in which the primary outcome is the clinical response to the intervention at 4 weeks, as measured by a dry mouth severity score (numeric rating scale from 0 to 10). Other outcomes, as measured by questionnaires over a 12-week follow-up period, include durability of the effect, impact on quality of life and, adherence and acceptability of the intervention. In addition, the feasibility and cost-effectiveness are evaluated by means of questionnaires and focus groups with healthcare professionals, and interviews with patients. DISCUSSION: This study investigates the effectiveness and feasibility of two interventions for dry mouth symptoms in patients with life-limiting conditions or frailty. Due to the large-scale and mixed-method nature of the study, this study will also improve our understanding of dry mouth and its relating factors and of the patients' and healthcare professionals' experiences with symptoms, care and guidelines of dry mouth, including any perceived barriers and facilitators. TRIAL REGISTRATION: NCT05964959 & NCT05506137.