Prevalence of and related risk factors in oral mucosa diseases among residents in the Baoshan District of Shanghai, China

Research objectives

We used multistage stratified random sampling and field surveys to investigate the population of the Baoshan District of Shanghai in 2014. Four neighborhood committees were selected by a random cluster method, and entire families were selected for oral examination according to house number. We calculated maximum sample size using the OMD prevalence rate of 14.93% (range 14.93–29.3% according to (Xu et al., 1981; Cao et al., 1988). The formula [n = t2∗p∕d(1 − P) 2, p = 14.93%, d = 0.1 * p, take α = 0.05, t = 1.96] yielded a theoretical figure of 2,189 people. Unfortunately, this study was only able to sample 653 people. We conducted follow up with patients 4 years later to assess the long-term effects of persistent risk factors on the course of the disease. The procedures were approved by the Ethical Committee of the Stomatological Hospital Affiliated to Nanjing Medical University (PJ2014-132) and the ethical committee of Shanghai First People’s Hospital (2019KY063).

Questionnaire design and oral mucosa examination

The survey was prepared according to the World Health Organization’s (WHO, 2013) oral health assessment form guidelines. It was designed to evaluate the condition of the oral mucosa. The questionnaire includes demographics (name, gender, age, nationality, place of birth, length of residence in Shanghai, education level, marital status, occupation, etc.), smoking habits (current, former or never), drinking habits (current, former or never), systemic disease (diabetes, hypertension, coronary heart disease and cerebrovascular diseases), and mental status (stress, anxiety). For the purposes of the survey, we considered systemic disease to be identified if the resident was diagnosed by a doctor. Gestational diabetes was not included in this survey.

Oral mucosa examination followed the clinical diagnostic criteria proposed by the WHO (Kramer et al., 1980). Portable halogen lamps, disposable retractors, and mouth mirrors were used in this study. When performing oral mucosa examinations, the intraoral and perioral mucosa and soft tissue were comprehensively examined for each subject in the following systematic order: lip, corner of mouth, cheek, tongue, bottom of mouth, hard and soft palate, alveolar ridge and gingiva. When residents were clinically diagnosed with OPMDs, including OLP or OLK, we referred them to our hospital for laboratory tests and biopsies. Expert pathologists confirmed the final diagnosis. Informed consent was obtained prior to the initiation of the examination. Inspectors were trained to ensure that guidelines for observation were interpreted uniformly and that mucosal diseases were documented correctly. Calibration exercises were repeated every month. Ten inspectors participated in the study, six of those participated throughout the whole study.

Statistical methods

All data were analyzed statistically using the SPSS 25.0 software package (Chicago, IL, USA). Two people were responsible for data entry and analysis. A X² test was used to compare the rates of risk factors. Logistic regression analysis was used to detect correlation between disease and risk factors. Results were considered significant if p < 0.05.

Survey results

A total of 653 permanent residents were surveyed in 2014, including 337 males and 316 females. We followed up with approximately 93% of those residents in the 2018 survey: 607 residents (311 men and 296 women). The remaining 7% were lost to follow up.

The education levels of the test subjects were mainly middle school (and below) level, mostly retired people. The average age of the respondents in 2014 was 66.05 years old (17–92), and the average age in 2018 was 67.38 years old (18–91).

Prevalence of OMDs

In the 2014 survey, a total of 60 people (9.19%) had OMDs, which included 12 cases of atrophic glossitis (1.84%), 11 cases of RAU (1.68%), nine cases of burning mouth syndrome (BMS) (1.38%), eight cases of OLP (1.23%), eight cases of traumatic ulcer (1.23%), six cases of furrowed tongue (0.92%), three cases of geographic tongue (0.46%), one case of cheilitis (0.15%), one case of angular cheilitis (0.15%) and one case of leukoplakia (0.15%). The results showed that the OMDs were mostly localized at the back of tongue, buccal mucosa, labial mucosa and gingival (gums).

In 2018, 58 people (9.56%) had OMDs (46 people were lost to follow-up, which included 41 with no OMDs and five with OMDs). Compared to 2014, there were ten cases of decreased OMDs and nine cases of new OMDs as follows: 11 cases of atrophic glossitis (1.81%, one case lost, no new), nine cases of RAU (1.48%, two cases lost, no new), seven cases with furrowed tongue (1.15%, none lost, one new), nine cases of OLP (1.48%, none lost, one new case of DM), seven cases of traumatic ulcer (1.15%, none lost, eight cases of decrease, seven case new), one case of geographic tongue (0.16%, one lost, one case of decrease). One case each of cheilitis, angular cheilitis and leukoplakia (0.16%, none lost, no increase, no decrease).

Distribution of diseases in males and females and in different age groups in 2014

The prevalence rate in females was higher than in males in cases of RAU, BMS and OLP (p < 0.05; Fig. 1). In addition, the overall prevalence of OMDs in females was also higher than in men (p < 0.05). The cases of RAU and BMS were statistically significant in different age groups. The prevalence of RAU in 15–29 year-olds and 30–39 year-olds was significantly higher than that in the older age groups (50–59, 60–69, 70–79) (p < 0.01), but there was no significant difference between the two groups (p > 0.05). We found BMS more frequently in people over 40 years old, prevalence increased with age, and was significantly higher in the 70–79 age group than in the 40–49 group (p < 0.01). OLP was detected in the population over 40 years old, and there was no significant difference among age groups (Fig. 2).

Effect of living habits and mental state on OMDs in 2014

Respondents generally had a light diet. There were 107 (16.39%) smokers (people who had smoked for over three years) and 93 (14.24%) who were drinkers (millet wine and beer). The rate of smoking (p = 0.01) and alcohol consumption (p = 0.00003) in persons with OMDs was higher compared to those with no OMDs (Fig. 3). Our survey showed that 87 people were had mental anxiety and 24 people felt higher than normal stress in life. Those with OMDs were had a higher rate of anxiety compared to those with no OMDs (p = 0. 0002). However, there was no statistically significant difference in stress between persons with OMDs and no OMDs (p = 0. 903) (Fig. 4). The sample group included 97.5% people in a stable family relationship, 28.1% with no friends and 36.8% having a little interpersonal communication. The vast majority (96.2%) of respondents had no adverse life experiences in past 12 months.

Analysis of risk factors related to OMDs and OLP in 2014

This study found that there was no significant difference in the prevalence of OMDs between men and women in the population of Baoshan, Shanghai. It also found that the occurrence and prevalence of OMDs, particularly atrophic glossitis, RAU, BMS and OLP, were positively correlated with increasing age among residents.

The study also found that rates of smoking, drinking and mental anxiety in the OMD population were significantly higher than in the healthy population, but that there was no statistical difference. Systemic diseases, such as cardiovascular and cerebrovascular hypertension (p = 0.025) and metabolic diseases or diabetes (p = 0.028), were closely related to OMDs. Systemic diseases such as cardiovascular and cerebrovascular hypertension (p = 0.025), and metabolic diseases diabetes (p = 0.028) were closely related to OMDs. The investigation group theorized that the high number of elderly patients would have proportionally higher incidence of dental cavities and removable dentures and presumed that incidence of traumatic ulcers would also increase proportionally (Table 1).

OLP was more common in the elderly age group (40–60 years) and occurred in more females than males. In this study, OLPs mostly occurred in the buccal region. The cause of OLP is complex and still unknown. The WHO defines OLP as a potentially malignant disease of the oral mucosa. Currently, there is no specific treatment for OLP in clinical practice. As a result, the course of the disease is prolonged and the condition often recurs. OLP may develop into cancer, which has a vital impact on patients’ physical and mental health. The results of the general epidemiological investigation showed that there were eight community residents (1.23%) with OLP: two males and six females (male to female ratio 1:3). OLP was significantly associated with age, smoking and diabetes mellitus (p < 0.01) (Table 2).