Adequate secretion of saliva is important as saliva has a range of functions (lubrication, protection, pH control, antimicrobial action, and defence) that are important to maintain oral health. A broad range of medications can affect salivary flow as can systemic and auto immune disease such as diabetes and Sjogren’s syndrome. Salivary flow is measured using unstimulated or stimulated approaches. There is no agreed definition of low salivary flow but a stimulated salivary flow rate of <0.7 mL/min or unstimulated rate of approximately ≤0.1 to 0.2 mL/min are usually considered to represent hyposalivation.
The aim of this review was to synthesise the available literature on the prevalence of hyposalivation in individuals aged ≥60 years.
Searches were conducted in the Medline/PubMed, Embase LILACS, Web of Science and Abstracts in Social Gerodontology databases with no restrictions on language or date. Observational studies evaluating the prevalence of hyposalivation in patients aged ≥60 years using unstimulated and stimulated salivary flow methods were considered. Two reviewers independently screened and selected studies. One review extracted data which was cross-checked by a second reviewer. Risk of bias was assessed using a checklist based on the Joanna Bridge Institute Critical Appraisal Checklist for Systematic Reviews and Research Syntheses. Prevalence of hyposalivation in adults ≥60 years was the primary outcome measure. meta-analyses were performed to determine the prevalence of hyposalivation using unstimulated and stimulated methods through a fixed and random effect model. The overall prevalence was also calculated
- 13 studies involving a total of 3885 patients were included.
- Sample sizes ranged from 28-800 patients aged from 60-100yrs.
- Studies were from Australia, Brazil, Croatia, Finland, Germany, Japan, Saudi Arabia, Sweden and the USA.
- 10 studies used an unstimulated method, 3 studies a stimulated approach and 4 both stimulated and unstimulated.
- 5 studies standardised collection time to the morning while 7 did not report collection time details.
- 2 studies were considered to be at high risk of bias, 2 a moderate risk and the remainder a low risk.
- Hyposalivation prevalence ranged from 10% to 64% for the unstimulated method and 13% to 75% in the stimulated studies.
- Meta-analysis for hyposalivation prevalence
- Overall = 33.37% (95%CI; 23.90 – 43.57).
- Unstimulated = 33.39% (95%CI; 21.08 – 46.96) [2,425 patients].
- Stimulated = 47% (95% CI 22.53-39.04) [1,495 patients].
The authors concluded: –
Despite known risk factors associated with hyposalivation in the older adults, our results indicate that the overall prevalence of hyposalivation in the older adults (aged ≥60 years) is 33.37%. When considering the stimulated saliva methods, the prevalence of hyposalivation was slightly lower (30.47%). These findings indicate a high prevalence of hyposalivation in elderly people, which could potentially directly impact oral status and quality of life in this population.
The reviewers have searched a good range of databases with no limitations so should have identified all the relevant studies. In the discussion they note that the data included in this meta-analysis was derived from non-institutionalised elderly a point which could have been highlighted in the exclusion criteria. Older patients are likely to have comorbid medical conditions and polypharmacy which could affect salivary gland function. Ideally future studies on hyposalivation should take into account the potential confounders of medication and institutionalisation as these are not adjusted for in this review. This review provides a useful summary of hyposalivation using both stimulated and unstimulated salivary samples. However, while hyposalivation may be measurable its clinical relevance is currently unknown as the subjective feeling of dry mouth and xerostomia does not seem to be directly associated with a reduction in salivary flow.
Pina GMS, Mota Carvalho R, Silva BSF, Almeida FT. Prevalence of hyposalivation in older people: A systematic review and meta-analysis. Gerodontology. 2020 Sep 23. doi: 10.1111/ger.12497. Epub ahead of print. PMID: 32965067.
Dental Elf – 24th Oct 2018