This study was a population-based cross-sectional study carried out from June to September 2016. Ghana is a country located on the West Coast of Africa and is divided into 16 administrative regions. With a population of 4,010,054 in 2010, the GAR is the second most populated administrative region and accounts for 16.3% of Ghana's population. The region is further divided into 16 districts (Fig. 1), which are sub-classified into two metropolitan, nine municipal, and five ordinary districts defined by a minimum population of 250,000, 95,000 and 75,000 respectively. Majority (90.5%) of its population live in urban localities with an annual urban growth rate of 3.1%.
The GAR was chosen for this study because it harbours the largest proportion of oral health personnel and clinics in the country. Within the region, 89% of the dental clinics are located in the two metropolitan areas and 5.5% each located in the municipal and ordinary districts. The region is therefore very diverse in terms of access to oral health care and is a rich source of information in comparing risk factors from respondents with good and poor access to oral healthcare. The target population was adults aged 25 years and above who reside in the GAR.
We used a stratified two-stage sample design to allow estimates of key indicators at the district level as well as urban and rural areas. The sampling frame was the 2010 population and housing census.
Sample size was estimated using a prevalence of 56% (8) for periodontal disease and a margin of error of 5% at 95% confidence level. An estimate of 379 was obtained but to mitigate the effect of possible sampling errors, due to the design, the standard error was increased by a factor of 1.5. Also, factoring a 25% non-response (9), a total of 712 was estimated. To ensure equal numbers from each EA, a total of 800 was estimated as the minimum sample to be recruited.
In the region, the 16 districts are each subdivided into enumeration areas (EA) with each EA being either urban or rural. We therefore stratified the region by urban and rural localities of residence, and by the three types of districts; Metropolitan, Municipal and ordinary District. A two-stage sampling methodology was used in selecting 800 households (Fig. 2). The first stage involved the random selection of 20 EA’s from the three district types, consisting of 14 urban EAs and 6 rural EAs. The selection was carried out using computer generated random numbers. At the second stage, a household listing of all households in each EA served as the sampling frame for the selection of 40 households, and one individual from each household was recruited. The households were then selected by systematic sampling proportional to size. The selected samples were, however, not self-weighting since the rural areas and the ordinary districts were over-sampled. (The metropolitan districts are all wholly urban and the ordinary districts had a smaller population). Thus a final weighting adjustment was done to provide estimates for each domain according to recommended strategy. (10) The selected participants for each EA were assembled at a prearranged venue where a mobile dental clinic with the research team carried out interviews, a physical and clinical oral examination.
A semi-structured questionnaire was used to collect information on the respondents’ background characteristics, socioeconomic status, attitudes and oral health habits. Their health state was also assessed by identifying disease conditions they had been diagnosed with.
Three dentists, 3 hygienists and 6 dental surgery assistants participated in a one-week training and calibration session, at the University of Ghana Dental School (UGDS) Clinic by a National Health and Nutrition Examination Survey (NHANES) dental examiner. Repeated measurements for inter-examiner reliability were performed. Following this, the whole research team including 4 interviewers underwent training on procedures for data collection.
Interviews were conducted using interviewer administered questionnaires. The questionnaires were pre-tested with 40 participants in a population with similar characteristics.
The questionnaire included modules on socio-demographics, risk factors for oral disease, chronic conditions and anthropometric measurements. They included:
Age, sex, ethnicity, religion, marital and educational status, place of residence (urban or rural), economic and health insurance status was obtained through self-report.
Oral health risk factors
Oral hygiene practices, dental attendance patterns, smoking and alcohol use.
Oral healthcare coverage: was derived by utilizing two questions from the questionnaire, (1) During the last 12 months, did you have any problems with your mouth and/or teeth? (2) During the last 12 months, did you receive any medical care or treatment from a dentist or other oral health specialist for this problem with your mouth and/or teeth? Oral healthcare coverage was defined as the proportion of individuals who expressed a need (as indicated by the first question) that answered the second question positively.
The height of the respondents was measured with a seca stadiometer and recorded in centimetres to the nearest 0.1cm. Their weight was measured with a seca 762 weighing scale in kilograms to the nearest 0.1kg. From these, body mass index (BMI) was computed as weight (kg)/height (metres)2. Obesity was defined as BMI ≥ 30 kg/m2, overweight as BMI ≥ 25 kg/m2 and < 30 kg/m2 and underweight as BMI < 18.5 kg/m2 (11).
A 203 cm non-elastic, plastic seca measuring tape with 1 mm divisions was used for the measurement of waist and hip circumferences. A high waist circumference was defined as waist circumference > 90 cm for males and > 84 cm for females. A high WHR or central obesity was defined as WHR > 0.90 for males and 0.85 for females (11).
In addition to a self-reported hypertension diagnosis, the blood pressure of all participants was measured using an OMRON 10 series blood pressure monitor model BP786N. In accordance with the WHO STEPwise approach to chronic disease risk-factor surveillance protocol (12), three measurements were taken and the average of the last two readings estimated. The respondent was considered to be hypertensive if the mean of the last two measurements was ≥ 140 mmHg (systolic BP) or ≥ 90 mmHg (diastolic BP), or if the respondent was currently taking anti-hypertensive medications.
Glycosylated Haemoglobin (HbA1c) was measured using A1CNow+®, (PTS Diagnostics, Whitestown, Indiana, USA). Diabetes was considered to be present if HbA1c was 6.5% or above, prediabetes if HbA1c was between 6.0 and 6.4% and normal if below 6.0% (13).
This consisted of a general oral examination, caries assessment and a periodontal examination.
The general oral examination consisted of a soft tissue assessment involving an evaluation of the soft palate, hard palate, gingival and buccal mucosa, muco-gingival folds, tongue, sub-lingual area, sub-mandibular area, salivary glands, and tonsilar and pharyngeal area. All teeth present were counted, and their absence including the presence of prostheses and retained roots were recorded. All teeth present were also assessed for dental caries and restorations.
A full mouth periodontal examination was then conducted on six sites of all teeth excluding the third molars with a manual periodontal probe (Hu Friedy PCP UNC-12).
Periodontal status was assessed by probing pocket depth (PPD), and clinical attachment loss (CAL). Six sites per tooth were assessed. The PPD was measured as the distance in millimetres between the free gingival margin (FGM) and the base of the pocket/sulcus. To obtain CAL, gingival recession/hyperplasia (the CEJ-FGM distance) was measured as the distance between the cemento-enamel junction and the free gingival margin. CAL was then computed at the analysis stage, as the difference at each site between the measures of pocket depth and the CEJ-FGM distance.
Gingivitis was defined as the presence of gingival bleeding on probing (BOP) in at least one site (14) and periodontitis was classified according to the CDC-AAP case definition (15).
Data were entered into Microsoft Excel for cleaning, recoding, and validation for completeness and data quality. Statistical analyses were performed to summarise the data in the form of frequencies, percentages, and tables. All the analyses were done using STATA 14 software (StataCorp. College Station, TX).
The study along with all its method and procedures have been performed in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Ghana Heath Service Ethical Review Committee (GHS-ERC:15/09/15) and the University of Ghana School of Medicine and Dentistry Ethical and Protocol Review Committee (CHS-Et/M.7-P4.7/2015–2016). Permission was obtained from the Metropolitan, Municipal or District Directors of Health Services for all the districts selected. The research was explained to all the participants after which their written informed consent was obtained from all of them before the study related procedures were carried out.