Patients
This study was conducted to evaluate the influence of oral health on frailty in elderly patients with type 2 diabetes. This is a retrospective study of data from Okamoto Internal Medicine Clinic, Shizuoka, Japan, collected from December 2019 to March 2020. The subjects of this study were patients with type 2 diabetes aged 75 years and older and those with gait disturbance were excluded.
Methods
Of the 229 patients enrolled, 111 eligible patients were surveyed by questionnaire for frailty, oral health status, and cognitive and living functions (Fig. 1). To evaluate oral health status, the oral frailty index-8 (OFI-8), an eight-question oral health assessment tool reported by Tanaka et al., was used [16]. The adjusted odds ratio with a 95%CI of the OFI-8 score to frailty was estimated. Adjusted odds ratios were calculated for pre-frailty, frailty, and individual frailty scores. In addition, factors influencing oral health were examined. Data on age, sex, BMI, duration of diabetes, and HbA1c were collected.
For the evaluation of frailty, a self-evaluation questionnaire developed by Yamada et al. consisting of five items—weight loss, gait speed, exercise frequency, short-term memory, and feeling of fatigue—was used [17]. Cases corresponding to 1 or 2 items were defined as pre-frailty, and cases corresponding to 3 or more items were defined as frailty.
Cognitive and living functions were evaluated using the Dementia Assessment Sheet for Community-based Integrated Care System-8 (DASC-8) items developed by Toyoshima et al [18]. Patients were classified into three categories (I, II, and III) determined by DASC-8 score—I: normal cognitive function and activities of daily living (ADL) independence; II: mild cognitive impairment or mild dementia or instrumental ADL decline, and basic ADL independence; and III: moderate or severe dementia or decreased basic ADL or many comorbidities or dysfunctions [18].
The OFI-8 score was the sum of the scores for each of the following questions below. Q1: Do you have any difficulties eating tough foods compared to 6 months ago? (2 points for Yes), Q2: Have you choked on your tea or soup recently? (2 points for Yes), Q3: Do you use dentures? (2 points for Yes), Q4: Do you often have a dry mouth? (1 point for Yes), Q5: Do you go out less frequently than you did last year? (1 point for Yes), Q6: Can you eat hard foods like squid jerky or pickled radish? (1 point for No), Q7: How many times do you brush your teeth in a day? (3 or more times/day) (1 point for No), and Q8: Do you visit a dental clinic at least annually? (1 point for No) [16].
Statistics
Descriptive statistics are expressed as n (%) and mean ± SD. The Kruskal-Wallis test was used to compare continuous variables, and the chi-square test was used to compare categorical variables. For the evaluation of factors influencing pre-frailty, frailty and individual frailty score categories, the adjusted odds ratio [95% CI] was calculated from multiple logistic analysis using the variables extracted by the stepwise method from the following variables: sex, age, duration of diabetes, HbA1c, OFI-8, DASC-8, and BMI. Furthermore, the scores for factors influencing frailty were converted into deviation values, and the relationship between the frailty score and change in the deviation value of each influencing factor was evaluated. For the evaluation of the factors influencing the OFI-8 scores, multiple regression analysis was used using the variables extracted by the stepwise method from the following variables: sex, age, BMI, duration of diabetes, HbA1c, DASC-8, and frailty score. For the influence of diabetic duration on oral health, an OFI-8 score ≥ 4 was defined as oral frailty [16] and a cutoff value was calculated using receiver operating characteristic (ROC) analysis. The two-sided α was set to be 0.05. Statistical analysis was performed using SPSS (IBM).