Risk factors and symptoms associated with xerostomia: a cross-sectional study

Authors


Dr Alessandro Villa
Dental Clinic
Department of Medicine, Surgery and Dentistry
University of Milano
Via Beldiletto 1/3
20142 Milano
Italy
Email:alessandro.villa@unimi.it

Abstract

Background:  The aim of this study was to examine the symptoms and risk factors associated with self-reported xerostomia.

Methods:  Data were collected from 601 self-administered questionnaires among dental clinic attendees. Logistic regression models to estimate odds ratios and 95% confidence intervals were used to investigate the association for exposures of interest, such as socio-demographic characteristics, self-reported symptoms, oral hygiene habits and xerostomia.

Results:  Participants reported having dry mouth in 19.6% of cases. Xerostomia was associated with a significant increase in the odds of having dry lips, throat, eye, skin and nose. Patients with self-reported xerostomia were three times more likely to drink water to swallow food than were patients without xerstomia. Older individuals were significantly more likely to report dry mouth, and the prevalence of xerostomia increased with advancing age. The prevalence of xerostomia in patients taking one or more drugs was significantly higher compared to medication-free patients, and increased with increasing numbers of medications used. Finally, individuals with a nervous or mental disorder, or who wore removable dentures were five times more likely to develop xerostomia than patients without disorder or dentures.

Conclusions:  Dentists should be familiar with the symptoms of xerostomia and be prepared to take an active role in the diagnosis, management and treatment of the oral complications.

Abbreviations and acronyms:
OR

odds ratio

SGH

salivary gland hypofunction

Introduction

Xerostomia is a common subjective complaint of dryness in the mouth1 and is distinctly different to alterations in salivary flow rate (usually described as salivary gland hypofunction, SGH). These two conditions are not necessarily related; several studies show that people can have SGH, but do not report symptoms of dry mouth (xerostomia), and similarly people who report xerostomia may have normal or high salivary flow.2 Xerostomia affects people socially and emotionally, and may reduce their quality of life.3 The presence of xerostomia with a low or altered salivary flow may place patients at a higher risk of dental caries, gingivitis, erosion and ulceration of mucosal tissues, oral candidiasis, dysgeusia and dysphagia.4,5 A reduction of saliva may lead to complaints of dry mouth, halitosis and oral burning sensation. Other manifestations may include an increasing aversion to dry foods, difficulty with swallowing dry foods, or increased need to sip or drink water when swallowing.6 In addition, the wearing of dentures is severely complicated.7

The major causes of xerostomia among dental patients are the use of medications, and head and neck radiation therapy.4 Radiotherapy may lead to sialadenitis, parenchymal loss, and then to xerostomia. The extent of involvement is dependent upon the radiation dose received, the time over which the dose was received, the area and volume irradiated, the energy of the radiation and the type of radiation. Both stimulated and resting saliva volumes are decreased by radiotherapy but some improvement can be expected over time. Similarly, the severity of dry mouth increases with increasing duration of treatment, number of medications used and dosage. Other possible causes of dry mouth include uncontrolled diabetes, chronic graft-versus-host disease, Sjögren’s syndrome, vasculitis, dehydration, malnutrition, psychogenic conditions and immunodeficiencies.8,9 The evidence for chemotherapy or normal ageing as causative factors is still controversial.

The symptomatic management of xerostomia involves the use of saliva stimulants, saliva substitutes, oral lubricants, non-irritating toothpaste, sugarless sweets containing citric and malic acid, chewing gums, pilocarpine and increased fluid intake.10

Xerostomia represents a serious problem with medical and oral consequences. As such, dentists can identify early symptoms to improve patient oral comfort and function. The aim of this study was to investigate the perception of dry mouth among dental patients and explore the possible risk factors and symptoms associated with this condition.

Materials and methods

Study population and recruitment

From September 2009 to June 2010, patients were recruited from the Unit of Oral Diagnosis at the University of Milan, Italy and were invited to complete a questionnaire. Participants were selected sequentially based on the following inclusion criteria: (1) aged 18 years or older; and (2) ability to read, understand and answer the questionnaire. All patients signed informed consent documents.

The questionnaire

All patients received the same questionnaire at the dental clinic; although the questionnaire was self-administered, a dental student was available if any question(s) arose. The first section of the questionnaire collected socio-demographic information including gender, country of birth, age, education level, tobacco and alcohol habits, and self-reported medical history. Medication data were collected asking for the name of drug(s) taken daily. The second section assessed oral hygiene such as daily use of toothpaste, dental floss, inter-dental brush and mouthwash. The third section of the questionnaire asked patients if they had any oral lesion(s) or experienced burning mouth, dry mouth and/or halitosis. They were also asked to report the frequency, severity and duration of dry mouth symptoms. Responses for these items were ‘never’, ‘seldom’, ‘sometimes’ and ‘often’. Another question assessed whether participants wore a removable denture. Finally, the last section queried whether the participant had dry lips, throat, eyes, skin and/or nose. In addition, patients were asked to report if they woke up at night to drink water and/or if they drank water to facilitate swallowing.

Statistical analysis

The distribution of socio-demographic characteristics, tobacco smoking (current smokers) and alcohol consumption (more than two drinks per day), medical history, oral hygiene habits and symptoms and oral conditions were evaluated. Age was divided into quartiles. Education was measured as the highest level of education achieved, which we described in four categories: (1) five years of school (primary school); (2) eight years of school (junior high school); (3) 13 years of school (high school); and (4) some college education or more (14 years or more of school).

Given the possible association between age and xerostomia, socio-demographic characteristics, smoking and alcohol consumption, medication and diseases, oral hygiene habits and self-reported symptoms were stratified by age (Tables 1 and 2).

Table 1.   Socio-demographic characteristics and medical history
Socio-demographic dataTotal n (%)Age category n (%)P for trend
(= 601)18–35 (= 176)36–50 (= 153)51–60 (= 101)60+  (= 167)
  1. aDue to small sample size America, Asia and Australia were collapsed into ‘Other’ category.

  2. *Alcohol consumption was defined as consuming an average of more than 2 glasses per day.

Gender
 Female304 (50.7)72 (40.9)86 (56.2)50 (50.0)94 (56.3)<0.05
 Male296 (49.3)104 (59.1)67 (43.8)50 (50.0)73 (43.7)
Country of birth
 Italy541 (90.0)152 (86.4)121 (79.1)97 (96.0)167 (100.0)<0.01
 Othera60 (10.0)24 (13.6)32 (20.9)4 (4.0)0 (0.0)
Education (years)
 553 (8.8)2 (1.1)3 (2.0)7 (7.0)41 (24.7)<0.01
 8128 (21.4)41 (23.4)27 (17.8)25 (25.0)35 (21.1)
 13288 (48.2)19 (10.9)38 (25.0)30 (30.0)38 (22.9)
 14 or more128 (21.4)113 (64.6)84 (55.3)38 (38.0)52 (31.3)
Medical history
Current smoker
 No436 (72.5)68 (40.9)39 (25.5)37 (36.6)21 (12.6)<0.01
 Yes165 (27.5)108 (59.1)114 (74.5)64 (63.4)146 (87.4)
Cigarettes/day
 0–570 (43.5)36 (53.7)10 (25.6)15 (41.7)9 (47.4)0.1
 6–1539 (24.2)16 (23.9)15 (38.5)15 (41.7)6 (31.6)
 15+52 (32.3)15 (22.4)14 (35.9)6 (16.7)4 (21.1)
Alcohol consumption
 Never224 (38.8)51 (40.9)66 (44.6)31 (33.3)74 (45.7)<0.01
 Yes*353 (61.2)119 (59.1)82 (55.4)62 (66.7)88 (54.3)
Medication intake
 No360 (59.1)155 (40.9)108 (70.6)66 (65.3)28 (16.8)<0.01
 Yes241 (40.9)21 (59.1)45 (29.4)35 (34.7)139 (83.2)
Number of medications/day
 190 (38.2)13 (68.4)23 (53.5)18 (51.4)35 (25.4)<0.01
 2–381 (34.3)4 (21.1)12 (27.9)6 (17.1)59 (42.8)
 >365 (27.5)2 (10.5)8 (18.6)11 (31.4)44 (31.9)
Diseases
 Hypertension120 (20.0)0 (0.0)12 (19.4)23 (39.0)85 (38.6)<0.01
 Cardiovascular58 (9.7)3 (21.4)9 (14.5)9 (15.3)36 (16.4)
 Diabetes39 (7.7)3 (21.4)8 (12.9)5 (8.5)22 (10.0)
 Thyroid39 (7.7)2 (14.3)13 (21.0)8 (13.6)16 (7.3)
 Nervous or mental 19 (7.5)1 (7.1)5 (8.1)1 (1.7)12 (5.5)
 Osteoporosis34 (5.7)0 (0.0)1 (1.6)6 (10.2)26 (11.8)
 Liver18 (3.6)1 (7.1)5 (8.1)5 (8.5)6 (2.7)
 Blood15 (2.5)2 (14.3)5 (8.1)1 (1.7)7 (3.2)
 Lung10 (1.7)2 (14.3)2 (3.2)0 (0.0)6 (2.7)
 Kidney7 (1.2)0 (0.0)2 (3.2)1 (14.3)4 (57.1)
Table 2.   Oral hygiene habits, symptoms and conditions of Italian dental patients
Oral hygiene habitsTotal n (%)Age category n (%)P for trend
(= 601)18–35 (= 176)36–50 (= 153)51–60 (= 101)60+  (= 167)
Daily use of toothpaste
 No27 (4.4)4 (2.3)5 (3.3)3 (3.0)14 (8.4)<0.05
 Yes574 (95.6)172 (97.7)148 (96.7)98 (97.0)153 (91.6)
Daily use of dental floss
 No461 (76.7)124 (70.5)114 (74.5)82 (81.2)138 (82.6)<0.05
 Yes140 (23.3)52 (29.5)39 (25.5)19 (18.8)29 (17.4)
Daily use of inter-dental brushes
 No568 (94.5)175 (99.4)148 (96.7)93 (92.1)148 (88.6)<0.01
 Yes33 (5.5)1 (0.6)5 (3.3)8 (7.9)19 (11.4)
Daily use of mouthwash
 No375 (65.6)129 (75.4)93 (63.3)62 (64.6)90 (58.1)<0.01
 Yes197 (34.4)42 (24.6)54 (36.7)34 (35.4)65 (41.9) 
Oral conditions and symptoms
Wearing removable denture
 No543 (90.4)176 (100.0)152 (99.3)87 (86.1)124 (74.3)<0.01
 Yes58 (9.6)0 (0.0)1 (0.7)14 (13.9)43 (25.7)
Self-reported oral lesion(s)
 No540 (89.9)172 (97.7)137 (89.5)91 (90.1)136 (81.4)<0.01
 Yes61 (10.1)4 (2.3)16 (10.5)10 (9.9)31 (18.6)
Self-reported burning mouth
 No547 (91.0)166 (94.3)135 (88.2)91 (90.1)151 (90.4)0.27
 Yes54 (9.0)10 (5.7)18 (11.8)10 (9.9)16 (9.6)
Self-reported halitosis
 No522 (86.9)156 (88.6)126 (82.4)84 (83.2)153 (91.6)0.05
 Yes79 (13.1)20 (11.4)27 (17.6)17 (16.8)14 (8.4)

Patients reported the name(s) of medication(s) they were taking. Antihypertensives, anticholinergics, antipsychotics, anti-inflammatory medications, bronchodilators and antidepressants are the most common drugs that can interfere with salivary secretion and composition.11 We then identified all the xerogenic medications and created a dichotomous variable for daily medication intake. ‘Dry mouth’ was evaluated overall and then stratified by duration and frequency.

We used logistic regression models to estimate odds ratios (OR) and 95% confidence intervals (CI) to investigate the association of exposure of interest, such as participants’ characteristics and self-reported symptoms with the primary outcome (dry mouth). We fitted the initial full model with all of the participants’ characteristics, then reduced the model sequentially by removing variables whose results were not significant at the p = 0.20 level. Heterogeneity was assessed by use of the χ2 test. All p-values reported were considered statistically significant at p < 0.05.

Results

A total of 601 questionnaires were collected (296 males). Overall, patients ranged in age from 18 to 88 years, with a median age of 47 (interquartile range 32–63 years). The majority of participants were Italian (90.0%). Around 21% of patients completed university, 48.2% had a high school diploma, 21.4% completed junior high school and 8.8% reported five years of education. Approximately 28% of the study population reported current smoking, and alcohol consumption was reported by 61.2% of subjects (Table 1). Among current smokers, 43.2% smoked from 0 to 5 cigarettes per day, 24% smoked 6–15 cigarettes per day and 32.3% reported smoking more than 15 cigarettes daily. Nearly 49% were taking systemic medication. Daily medication use and daily number of drugs increased significantly with age (data not shown). Hypertension was present in 20.0% of individuals. Less than 10.0% of patients were affected by cardiovascular disease, followed by diabetes (7.7%), thyroid (7.7%), nervous or mental disorder (7.5%) and osteoporosis (5.7%).

When oral hygiene habits were considered (Table 2), the majority of individuals (95.6%) brushed their teeth with toothpaste, 23.3% reported daily dental flossing, and 34.4% used mouthrinsing products. Nearly 10.0% of patients reported wearing a removable denture. Oral lesions were present in 10.1% of individuals. Participants most frequently reported having dry mouth (19.6%); the reported burning sensation and halitosis were 9.0% and 13.1%, respectively. In stratified analysis, when age was considered, significant differences were observed for socio-demographic data, medical history (Table 1), some oral hygiene habits and self-reported oral symptoms (Table 2). Xerostomia was reported by the majority of the individuals (57.0%) to occur during the day and by 45.3% seldom to occur; the sensation of dryness in 51.4% of patients decreased while eating (data not shown). Detailed data on the frequency of other symptoms that were considered relevant to xerostomia are reported in Table 3.

Table 3.   Relation of dry mouth risk and self-reported symptoms and habits
 TotalDry mouthOdds Ratio (95% CI)P value
NoYes
Dry lips
 No124 (49.2)99 (79.8)25 (20.2)1.0<0.01
 Yes128 (50.8)73 (57)55 (43)2.9 (1.7–5.2)
Dry throat
 No157 (62.3)126 (80.3)31 (19.7)1.0<0.01
 Yes95 (37.7)46 (48.4)49 (51.6)4.3 (2.5–7.6)
Dry eyes
 No185 (73.4)137 (74.1)48 (24.9)1.0<0.05
 Yes67 (26.6)35 (52.2)32 (47.8)2.6 (1.5–4.7)
Dry skin
 No158 (62.7)124 (78.5)34 (21.5)1.0<0.01
 Yes94 (37.3)48 (41.9)46 (48.9)3.5 (2.0–6.1)
Dry nose
 No175 (69.4)134 (76.6)41 (23.4)1.0<0.01
 Yes77 (30.6)38 (49.4)39 (50.6)3.3 (1.9–5.9)
Wake up to drink water
 No135 (53.6)98 (72.6)37 (27.4)1.00.11
 Yes117 (46.4)74 (63.2)43 (36.8)1.5 (0.9–2.6)
Drink water to facilitate swallowing
 No181 (71.8)137 (75.7)44 (24.3)1.0<0.01
 Yes71 (28.2)35 (49.3)36 (50.7)3.2 (1.8–5.7)
Self-reported oral lesion(s)
 No540 (89.9)451 (83.5)89 (16.5)1.0<0.01
 Yes61 (10.1)32 (52.5)29 (47.5)4.6 (2.6–7.9)

Dry mouth sensation was associated with a significant increase in the odds of having dry lips, dry throat, dry eyes, dry skin and dry nose (Table 3). Compared to patients without xerostomia, patients with xerostomia were three times more likely to drink water to swallow food (OR: 3.2, 95% CI 1.8–5.7) and around five times more likely to have an oral lesion (OR: 4.6, 95% CI 2.6–7.9). Older individuals were significantly more likely to report dry mouth compared to those who were younger (p < 0.01), and the risk of having xerostomia increased with increasing age (Table 4). The prevalence of xerostomia in patients taking one or more drugs was 2.2 higher compared to medication-free patients (OR: 2.2, 95% CI 1.5–3.4), and increased with increasing number of medications used (16.7% vs. 33.3% vs. 36.9%; p < 0.01). Finally, individuals with a nervous or mental disorder, or those who wore removable dentures were five times more likely to report xerostomia (OR: 5.4, 95% CI 1.9–14.7 and OR: 5.1, 95% CI 2.9–8.9, respectively) than patients without disorder or dentures.

Table 4.   Multivariate analysis of associations with dry mouth
 Dry mouthOdds Ratio (95% CI)P value
NoYes
  1. aP-value for trend.

Age category
 18–35153 (86.9)23 (13.1)1.0<0.01a
 36–50134 (87.6)19 (12.4)0.9 (0.5–1.8)
 51–6075 (74.3)26 (25.7)2.3 (1.2–4.3)
 60+117 (70.1)50 (29.9)2.8 (1.6–4.9)
Alcohol consumption
 No172 (76.8)52 (23.2)1.00.16
 Yes288 (81.6)65 (18.4)0.8 (0.5–1.1)
Medication intake
 No308 (85.6)52 (14.4)1.0<0.01
 Yes175 (72.6)66 (27.4)2.2 (1.5–3.4)
Number of medications/day
 175 (83.3)15 (16.7)1.0<0.01a
 2–354 (66.7)27 (33.3)2.5 (1.2–5.1)
 >341 (63.1)24 (36.9)2.9 (1.4–6.2)
Liver disease
 No386 (78.9)103 (21.1)1.00.07
 Yes11 (61.1)7 (38.9)2.4 (0.9–6.3)
Blood disease
 No473 (80.7)113 (19.3)1.00.17
 Yes10 (66.7)5 (33.3)2.1 (0.7–6.2)
Nervous or mental disorder
 No166 (71.2)67 (28.8)1.0<0.01
 Yes6 (31.6)13 (68.4)5.4 (1.9–14.7)
Osteoporosis
 No460 (81.1)107 (18.9)1.00.06
 Yes23 (67.6)11 (32.4)2.1 (1.0–4.3)
Daily use of mouthwash
 No308 (82.1)67 (17.9)1.00.05
 Yes148 (75.1)49 (24.9)1.5 (1.0–2.3)
Wearing removable denture
 No454 (83.6)89 (16.4)1.0<0.01
 Yes29 (50.0)29 (50.0)5.1 (2.9–8.9)

None of the patients received radiation or chemotherapy. No significant associations were observed for the following variables: gender, education, smoking and alcohol consumption, hypertension, cardiovascular diseases, diabetes, thyroid diseases, osteoporosis, liver diseases, blood disorders, lung and kidney diseases, oral hygiene habits, and burning mouth sensation or halitosis.

Discussion

This study investigated the prevalence of and risk factors for dry mouth among a large number of dental patients. Self-reported xerostomia was present in about 20% of individuals, and the sensation of oral dryness increased significantly with age. This is probably due to a higher number of medications taken among the elderly compared to younger individuals.12,13 Firstly, our results show that there was a significant increase in self-reported xerostomia with increasing number of xerostomic medications being taken. This confirms what has been reported previously in other studies.14–16 Therefore, the geriatric population is more likely to be affected by dry mouth. Of note, dry mouth symptoms significantly increased in patients affected by mental or nervous disorders. It may be that these individuals took antipsychotic, tricyclic antidepressant, anxiolytic, sedative or anticonvulsant medications, which are well known for their antisialologic effects and thus cause dry mouth.2 Secondly, the logistic regression suggests that there was an association between age and xerostomia independent of the effects of the number of medications.

Drug-induced xerostomia has been reported to contribute to difficulty with swallowing and chewing.6,17 Our findings show that patients with a dry mouth sensation were three times more likely than those not reporting xerostomia to drink water to swallow certain foods. Patients with swallowing complaints may exhibit lower saliva production rates than those without complaints.18 As such, in order to compensate the reduced amount of saliva, individuals usually feel the urge to drink frequently while they eat. Also, xerostomia was strongly correlated with wearing removable dentures. Niedernicier and colleagues19 reported that individuals who wore dentures continuously showed significantly severe signs of inflammation compared to a control group without dentures. Thus, the consequent reduction rate of saliva secretion from palatal salivary glands contributes to xerostomia.

Our findings suggest that patients suffering from xerostomia may experience dry lips, throat, eyes, skin and nose. These symptoms could alert the dentist to a more serious problem, such as Sjögren’s syndrome. Sjögren’s syndrome is a systemic autoimmune disease characterized by chronic inflammation and subsequent destruction of the exocrine glands, including those found in the nose, skin, vagina, and respiratory and gastrointestinal tracts.20 Dentists may be the first health care providers to encounter the early signs of Sjögren’s syndrome. Therefore, they should be familiar with the manifestations of the disease and be prepared to take an active role in the diagnosis, management and treatment of the oral complications, and eventually consult a rheumatologist if the symptoms persist.

This cross-sectional study has its limitations. First, approximately half of the participants did not answer the section of the questionnaire that asked whether they had dry lips, throat, eyes, skin, and/or nose. Therefore, it is possible that some clinically important associations were not detected because of the low numbers of remaining respondents. Second, our study population was recruited from a dental clinic nested within tertiary referral centres. Thus, the results of this study likely represent an overestimate of the prevalence of self-reported xerostomia. Population-based studies are then warranted.

In conclusion, dentists should carefully review patients’ medical history. Life expectancy has greatly increased in the last century and there will be increasing numbers of people with acute and chronic diseases;21 the changes that occur with ageing make people more likely to suffer medication-related problems.22 Our study underlines the importance of evaluating the use of xerostomic medication, especially in elderly individuals, and asking xerostomia-related questions as part of the dental history. This is extremely important given that 1 in 5 patients suffer from this problem. Oral health care practitioners have the unique opportunity to detect xerostomia and provide appropriate treatment towards improved well-being.

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