Study Area and Period
A hospital-based unmatched case-control study was conducted among women attending gynecologic Out Patient Department (OPD) in Nekemte town, from May 1 to July 30/2019. Nekemte town, the capital city of East Wollega zone is found at 331 km west of Addis Ababa. According to the 2018 Nekemte town health Office report, the total population of Nekemte town was 127,380 of which 51.03%, 49.97%, 16.4%, and 3.47% comprised of male, female, under-five children and pregnant women respectively. The dominant ethnic group is Oromo. There are two public hospitals in the town namely Nekemte specialized hospital and Wollega University referral hospital. These hospitals give services including Obstetric and gynecologic services to nearly 5 million people in western Ethiopia and adjacent areas. They have well-organized gynecology and obstetrics departments which are led by 7 gynecologists and 15 general practitioners. These two hospitals provide uterovaginal prolapse and other surgical interventions.
All women attending gynecologic OPD at public hospitals in Nekemte town were the source population.
All women attending gynecologic OPD at public hospitals in Nekemte town during the study period. Cases were women with grade II, III & IV uterovaginal prolapse. Controls were those women free from uterovaginal prolapse but with some other gynecologic disease during the same study period. All women aged more than 18 years attending OPD during the study period were included in the study. However, women with grade I UVP, women with a total abdominal hysterectomy and vaginal hysterectomy, critically ill women, and women with mental problems were excluded from the study.
Sample Size Determination and sampling procedure
The sample size was calculated using Epi-info software version 7 using sample size determination for unmatched case-control studies. The parameters that were used to calculate sample size were; Confidence level 95%, power 80%, control to case ratio of 3: 1, the proportion of controls with exposure 6.2%, the proportion of cases with exposure 18.5%, and Odd Ratio of 3.1. It was calculated from the study conducted in Bahir Dar town, North West Ethiopia by taking BMI (< 18.5 kg/m2) as one of the main exposure variables for pelvic organ prolapse that provide the maximum sample size . Therefore, it yields 78 cases and 232 controls. Adding a 10% non-response rate, the final sample size becomes 341 (86 cases and 258 controls).
Two hospitals in Nekemte town were included because they were providing surgical intervention for cases of UVP. Then based on the number of clients who visited the gynecologic OPD of these two hospitals during the previous three months (60 cases and 358 controls for Wollega University Referral hospital, and 45 cases and 308 controls for Nekemte specialized hospital), the sample size was proportionally allocated to each hospital. Finally, cases in the two hospitals were included consecutively and three controls for each case were selected using a systematic sampling method.
Uterovaginal prolapse is defined as the descent of either of the uterus, cervix, vagina or associated structures such as bladder and rectum(1). Inter-pregnancy interval was defined as the interval between the most recent previous childbirth and the starting time of pregnancy for the current child as reported by the mother at the time of the interview. In this study, the women faced labor-intensive work if she reported frequent engagement to works like lifting and carrying heavy objects. Chronic cough is defined as a cough that lasts two months or more. Chronic constipation is defined as a stool frequency of less than three per week that lasts several months or having difficulty passing stools. In this study, abortion is defined as either spontaneous or induced termination of pregnancy before fetal viability (before 28 weeks of gestational age according to Ethiopian context).
Data Collection Tools and Procedures
Data on socio-demographic, obstetric, gynecologic, and medical history were collected by using a pre-tested structured interviewer-administered questionnaire which was developed by reviewing different literatures [13, 27, 30, 31,32]. Four BSc nurses and two MSc supervisors were recruited and trained for data collection. All questionnaires were checked for completeness daily by the supervisors.
Physical measurement was used to obtain data on the weight and height of women. In this regard, the weight of each woman was measured using a balanced beam in kg nearest to 0.1kg and height was measured using a measuring tape to the nearest 0.1cm. To diagnose uterovaginal prolapse, gynecologists working in Out Patient Department were used. Pelvic examination was done after a woman had emptied her bladder. The examination was done in a lithotomy position. To avoid intra-rater and inter-rater reliability, the authors had a thorough discussion with attending gynecologists on finding documentation.
Shaw’s classification system of uterovaginal prolapse was used for grading of the disease. In this classification system, the descent is classified into four grades; the first grade is the descent of the cervix into the vagina, second grade is the descent of the cervix into the introitus, third grade is the descent of the cervix outside the introitus, and the fourth grade is when the whole of the uterus is outside introitus .
Data Quality Assurance
The questionnaire was first prepared in English and then translated to the local language (Afan Oromo). The data collectors and supervisors were trained for two days on data collection and details of the study. A pretest was conducted on 4 cases and 12 controls at Mettu Karl Hospital which is located in southwest Ethiopia.
Data Processing and Analysis
After checking for completeness, data were entered using Epi Data version 3.1. It was then cleaned and exported to SPSS Version 20 for analysis. Frequency distribution and percentage were used to describe predictor variables. Also, descriptive statistics including mean and standard deviation were conducted to describe continuous variables. Bivariate analysis was used to examine the association between dependent and independent variables; Odds Ratios (ORs) and their 95% Confidence Intervals (CIs) were calculated. All variables that had a P-value of < 0.2 in the bivariate analysis were included in the multivariate logistic regression analysis model to identify determinant factors of uterovaginal prolapse. Statistical significance was set at a p-value of < 0.05. In the model development process, the existence of multi-collinearity was assessed to rule out the interaction among independent variables using the variance inflation factor (VIF). Accordingly, the result of VIF was close to one which showed minimal collinearity. The model was assessed for the goodness of fit using the Hosmer-Lemeshow test. Since the p-value for the Hosmer-Lemeshow chi-square was greater than 0.05(P=0.965), the model estimate was adequate to fit the data at an acceptable level.