1. Study framework
Attecoube is one of the thirteen municipalities in the District of Abidjan, located between the municipalities of Adjamé and Yopougon. It has a population of 207,586 and covers an area of 68.2 km2. Attecoube is divided into right and left banks, and comprises 35 neighborhoods and 5 villages. Economic life in this commune is essentially dominated by trade and craft activities. (Figure 1)
2. Type of study
This was a descriptive and analytical cross-sectional study conducted over a two-month period from February 15, 2022 to April 15, 2022 in the Attecoube Lagune neighborhood.
3. Population
The study population was made up of residents of the Attecoube Lagune neighborhood, living between Banco Bay and Peace Boulevard.
Inclusion criteria
Residents aged 18 and over who gave a positive opinion were included in the study.
Non-inclusion criteria
Pregnant women, sick people, non-consenting residents and anyone unable to perform a spirometry test were excluded from the study.
4. Sampling and sample size
Starting from the center of the district, the right-hand side of the entrance to the Naval Training Center (CNI) was randomly selected as the starting point for data collection. We progressed in the direction of the interchange, with a sampling step equal to 2. We proceeded in this way to the right and left to visit the selected concessions. Within each concession, all individuals who met the inclusion criteria were exhaustively enrolled.
The StatCalc program in Epi Info version 7.2.1 was used to calculate our minimum sample size. A minimum sample size of 153 was obtained. The elements used to calculate the minimum sample size were:
- Total population of Attecoube Lagune = 2,700 (Adjamé-Plateau-Attecoube District Report, 2021).
- Prevalence of respiratory diseases in Attecoube = 12%. (District Adjamé-Plateau-Attecoube report, 2021).
- Alpha risk = 5%.
- Confidence interval = 95%.
With a 10% increase, our final sample size was 168 people.
5. Data collection
As part of this study, three investigators, all students, received two days' classroom training on the research protocol and the various data collection tools and media. This training verified their understanding of research procedures (recruitment, consent and follow-up). In addition, a pre-test of the data collection form was carried out on February 10, 2022 in the Attecoube Sebroko neighborhood, and enabled the various shortcomings to be corrected. In addition, spirometry was carried out by a team consisting of a nurse and a doctor, both specialists in functional exploration and highly experienced.
Data collection took place in two phases. The first phase involved completing a questionnaire with each subject included in the study. The questionnaire collected information on socio-demographic characteristics, length of residence in the neighborhood, smoking habits, degree of exposure to pollution and health data.
The respiratory symptoms sought were those suggestive of asthma or chronic obstructive pulmonary disease (dry cough, wheezing, dyspnea and chest tightness), and rhinoconjunctivitis (rhinorrhea, nasal obstruction, nasal tingling, sneezing, lacrimation, ocular redness).
The second phase consisted in performing pulmonary auscultation and spirometry on each subject included in the study. Spirometry was performed using a Winspiro PRO6.5 MIR portable spirometer, followed by a reversibility test performed after inhalation of a 400 µg dose through an inhalation chamber. This test was carried out in accordance with the recommended guidelines of the American Thoracic Society (ATS) by two technicians (a nurse and a doctor) who were well trained to perform the said test.
The parameters measured were: forced vital capacity (FVC) in liters, forced expiratory volume in one second (FEV1) in liters per second and the Tiffeneau ratio (FEV1/FVC) expressed as a percentage.
The pathological threshold was defined by a fall of more than 20% in FEV1, FVC, the pathological threshold of the Tiffeneau ratio was defined by a fall of more than 12% (FEV1/FVC < 80% of predicted) according to the ATS/ERS Criteria.
The theoretical standard used is that of the African ethnic group incorporated into the spirometer software, which takes into account the subjects' sex, age, weight and height.
6. Operational definition
- Obstructive ventilatory disorder (OVD) is defined by a FEV1/FVC ratio of less than 80% of predicted.
The severity of the disorder is assessed on the basis of FEV1
- FEV1 > 80%: mild
- FEV1 50-80%: moderate
- FEV1 30-50%: severe
- FEV1 < 30%: very severe
- Reversibility of obstruction: gain in FEV1 of more than 12% (relative value) and 200ml (absolute value).
7. Data analysis
Univariate analysis was used to describe the variables: age, gender, height, weight, smoking, BMI, length of residence, occupation, level of education, level of exposure to pollution, respiratory symptoms (cough, dyspnea, wheezing, chest tightness) and family history of asthma.
The dependent variable: COPD (non-reversible TVO after beta 2 mimetic inhalation) was obtained from the results of spirometry performed on the inhabitants of Attecoube Lagune neighborhood.
A bivariate analysis was used to search for possible links between the dependent variable (COPD) and the independent variables (age, sex, smoking status, length of residence, level of exposure, occupational activity and level of education).
Independent variables with a significance level p ≤ 0.20 were included in the multivariate analysis.
Multiple logistic regression models were constructed to search for a link between the dependent variable and the selected independent variables. The top-down stepwise logistic regression method was adopted with (p < 0.05).
8. Ethical considerations
Verbal and informed consent was obtained from the respondents, before proceeding with the interviews. The questionnaire was only administered once consent had been obtained. Anonymity and confidentiality were respected, and initials were used instead of names. Interviews were conducted in French or the local language, and in private locations to ensure confidentiality. Approval for the study was granted by the internal ethics committee of the National Institute of Public Health and the District Sanitaire Adjamé -Plateau - Attecoube.