Discussion
Saliva is an essential component for the maintenance of normal oral health.20,21 Decreased saliva production causes problems, including difficulties with speech, mastication, dysphagia, changes in taste, dental caries, impaired use of prostheses, recurrent infections, halitosis, deterioration of soft tissues, and compromised QOL.22,23 Among patients with a diagnosed SDS abnormality who were seen at this facility during FY 2015, the prevalence of xerostomia was only 1.5%. However, the true prevalence and incidence of xerostomia among veterans is not known. Given the role of xerostomia as a common risk factor for SDS problems and the polypharmacy exhibited by those presented here with SDS problems, it is probable that xerostomia was underreported in this veteran cohort.
Additionally, although salivary acinar cells are known to atrophy with age, as is consistent with this xerostomia cohort’s average age (SD) of 69.3 (12.6) years, the development of dry mouth is a multifactorial process. The current scientific literature asserts that most salivary loss is due to local and systemic diseases, immunologic disorders, external radiation, and as was highlighted by this study, multiple prescription and nonprescription medications.24-26
It has also been demonstrated previously that dry mouth complaints and low salivary flow rates are directly proportional to the number of medications taken by patients.2,27-30 Polypharmacy is therefore an area of great interest, and ≥ 40 categories of xerogenic medications have been identified by investigators such as Sreebny and Schwartz.31 Among those, some of the most xerogenic medication classes include antihypertensives, antiulcer agents, anticholinergics, and antidepressants, are all very commonly consumed in this cohort of patients with dry mouth (58.7%, 42.0%, 47.1%, and 38.4%, respectively). The medication regimens within this cohort of veterans with xerostomia were prime examples of polypharmacy as each patient took an average (SD) of 10.4 (7.2) medications, 39.9% took ≥ 12, and 72.5% of patients with xerostomia were taking ≥ 6 prescription drugs during a 1-year period.
Given the dangers of polypharmacy, a more conservative approach to prescribing medications could feasibly help with preventing xerostomia and SGH. In practice, while clinicians try to avoid prescribing anticholinergics, antimuscarinics, and antihistaminergic drugs for geriatric patients, they are tasked with the complex management of medication adverse effects (AEs) when dealing with multiple health conditions. The clinicians’ primary responsibilities are to follow the standard of care and not to introduce unnecessary harm when managing patients, but they also must push for, stay abreast of, and conduct more basic research and clinical trials to inform, adjust, and improve our current standard.
Research into polypharmacy and its role in inducing dry mouth is ongoing. Twenty years ago, Thomson and colleagues identified reduced salivary flow in patients who used antianginals, thyroxine, diuretics, antidepressants, and medications for asthma, while only 5 years earlier Loesche and colleagues reported the role of antiulcer medications, such as proton pump inhibitors, in the development of xerostomia.2,32 Within the past 5 years, Viljakainen and colleagues and Ohara and colleagues have echoed some of those findings by identifying associations between xerostomia and agents that impact digestive organs.33,34 A strong association recently was identified between the use of antipsychotic drugs and xerostomia.35 Additionally, when attributing xerostomia to polypharmacy, the interaction between medications is often overlooked in favor of considering the raw number of prescriptions taken. Whereas 1 medication alone may not have drying properties, combinations of medications might be more likely to induce xerostomia. Thomson and colleagues suggested such a situation regarding the interaction between thyroxine and diuretics.36 Future studies should focus on identifying viable substitutes for existing medications that reduce risk for xerostomia without compromising the management of other serious conditions.