Dysmenorrhea Symptoms Interference Scale (DSI) in Serbian - Translation and psychometric properties evaluation.

Dysmenorrhea is defined as painful menstruation. The typically cramping pain may radiate to the thighs or lower back and be accompanied by nausea and vomiting, headache, diarrhea, fatigue, dizziness, and breast tenderness. The pain starts with the onset of menstruation and usually resolves within two or three days. Dysmenorrhea mostly occurs in adolescents (12–24 years) and young adults (up to 29 years of age) [ 1 – 3 ]. It affects 20–90% of women during the reproductive age, but regional and national estimates are lacking due to differences in the definitions and dysmenorrhea severity levels in previous investigations. Prevalence of dysmenorrhea in European ranges from 45–97% in general population and from 41–62% among hospitalized patients. In studies that included women with occasional and light symptoms rate of dysmenorrhea was over 80%. On the other hand, 10–15% of women have severe dysmenorrhea each month which can disturb normal daily activities at work, home, or school [ 4 – 6 ]. Risk factors for dysmenorrhea include smoking, high or low body mass index, younger age at menarche, longer menstrual cycles, longer and heavier menstrual flow, nulliparity and high level of stress [ 7 , 8 ]. If there is no underlying pelvic pathology or anatomic variant that might be the cause of pain the dysmenorrhea is classified as primary. Contrary, secondary dysmenorrhea is associated with different gynecological conditions out of which the most common causes of painful menstruation are endometriosis, adenomyosis or myoma. The adequate early diagnosis and distinction between primary and secondary dysmenorrhea is important for choosing optimal therapy and predicting potential complications [ 9 – 11 ]. The pathophysiology of primary dysmenorrhea is still under investigation, but it is mostly considered to be caused by rise in prostaglandin levels which lead to increased uterine pressure and contractions. Impaired uterine perfusion, ischemia, hypoxia due to contractions of higher intensity and metabolites from anaerobic metabolism also contribute to dysmenorrheal [ 2 , 12 ]. Severe dysmenorrhea can significantly impair women’s daily activities, sleep, concentration and productivity, relationships with family and friends, as well as the overall feeling of quality of life [ 3 , 4 ]. Studies reported that around 40% of women carried out fewer activities, 50% avoid exercising while some were even unable to do anything during painful menstruations. Sleep quality worsens during menstruation compared to other menstrual cycle phases. Presence of the pain significantly impacts academic performance (primary and secondary school as well as university education). Therefore, dysmenorrhea is usually associated with increased levels of anxiety and depression [ 5 , 6 , 13 – 15 ]. To evaluate the severity of dysmenorrhea and the effects of its treatment validated outcome measures are needed. Although there are quite a few instruments for investigating pain levels, better data can be obtained by instruments specifically designed for dysmenorrhea patients that enable multidimensional assessment all of the symptoms and its interference with quality of life and daily activities [ 16 ]. Therefore, the Dysmenorrhea Symptoms Interference Scale (DSI) was developed. Currently, there are available translations of DSI into several languages, but few of them were adequately validated. Moreover, no translation for the Serbian language exists [ 17 , 18 ]. The Serbian southern province of Kosovo has had numerous socioeconomic, educational and health challenges as a result of previous armed conflict between Serbian (mostly living in North Kosovo) and Albanian communities (generally living in the remainder of Kosovo). Factors such as limited business opportunities and high rates of unemployment, ongoing ethnic tensions, migrations, the availability of inexpensive illicit substances and alcohol as well as the presence of foreign military and nongovernmental organizations increase the level of overall stress among the population [ 19 ]. Thus, it could be anticipated that different psychosomatic illnesses are prevalent in the population of Kosovo, including dysmenorrhea in young women, who are trying to obtain the best possible education in such difficult circumstances [ 20 ]. Therefore, the study aim was to translate, culturally adapt and validate the Dysmenorrhea Symptoms Interference Scale (DSI) in the Serbian language, which could be used in the everyday counseling of women with painful menstruations both in Kosovo and central Serbia.

The study incorporated 350 female students who in average had 20.58 + /- 1.97 years (range 18–25 years). Majority of students were studying medicine (82.9%). Dentistry was attended by 9.4% and nursing 7.7% of students. They were generally healthy (14.6% had chronic and 12.9% had gynecological illnesses), with regular menstrual cycles (89.1%), but no previous pregnancies (77.4%). Few investigated students used hormone contraception (3.4% only as contraception and 8% to treat menstrual cycle irregularities, premenstrual syndrome and/or dysmenorrhea). Investigated students mostly reported that dysmenorrhea symptoms were present since the time of menarche (66.0%) during almost all cycles (42%) and for the first two days of menstruation (77.7%). Majority of students stated that the pain was intensive but bearable (36.6%) although 57.1% of students regularly took analgesics for the pain. The simple literal translation was adequate for almost all DSI items and just minor changes were made during the process of translation and validation. Average DSI item scores are presented in Table 1 . Data were not normally distributed by standard means of assessment as well as (p = 0.001) multivariate normality testing (Mardia’s skewness and kurtosis p = 0.001). Still, thorough evaluation of skewness per item showed that it was appropriate for all items. There were no significant differences in the frequency of grades per item (1–5) in our sample. All of the items were graded with marks from 1 to 5 meaning that at least some of the investigated female students had all of the assessed complaints. Still, only 7.5% of students had a high final DSI score (above four). The highest average score was achieved for item #9 (mood), while items #2 and #8 (sleep and social activities) had the lowest average scores. As sampling was adequate (KMO = 0.885; Bartlet p = 0.001) factor analysis was performed. On EFA we obtained one factor for the Serbian DSI version just like in the original validation ( Table 2 ). The factor loadings and communality indices for all the items were >0.4. Total variance explained by the extracted factor was 64.16%. Parallel analysis confirmed that only one factor should be retained ( Table 3 ). Finally, CFA ( Fig 1 ) showed that for the obtained model (χ 2  = 234.617; df = 27; p = 0.001) all fit indices were appropriate ( Table 4 ). Cronbach’s alpha coefficient of the Serbian DSI version was 0.928 while McDonald’s omega coefficient was 0.951 indicating good internal consistency. Value of Cronbach’s alpha coefficient if item deleted was above 0.80 for all items ( Table 2 ). If the item #9 (mood) was deleted Cronbach’s alpha coefficient was the highest (coefficient = 0.929) while if item #7 (leisure activities) was deleted it was the lowest (coefficient = 0.913). Based on Hotelling’s T-Squared test, there was a significant difference between item scores (HT 2  = 345.803; F = 42.358; p = 0.001). The values of the CI-TC coefficients for the DSI in Serbian population were higher than 0.40 for all items, with the lowest of 0.601 for item #9 (mood). Consequently, all of the items were significant elements of the questionnaire. The Serbian version of DSI displayed an adequate convergent validity as its total score significantly correlated with DASS 21 total score (ρ = 0.520; p = 0.001). Moreover, DSI total score positively correlated with Depression (ρ = 0.453; p = 0.001), Anxiety (ρ = 0.441; p = 0.001) and Stress (ρ = 0.449; p = 0.001) domain scores of DASS 21. Significant differences were registered regarding DSI scores between students with mild and severe dysmenorrhea symptoms (F = 29.391; p = 0.001) which indicated that DSI can adequately differentiate patient groups.

The Serbian version of the Dysmenorrhea Symptoms Interference Scale was proven to be a valid and reliable specific instrument for assessing the impact of menstrual pain on a woman’s quality of life. As DSI has adequate psychometric properties it can be applied both in research and in broad clinical use to assess and classify dysmenorrhea symptoms of women from Serbia as well as to develop and test interventions for dysmenorrhea.

This prospective study was conducted at the University of Pristina, temporarily seated in Kosovska Mitrovica, over a two-month period (April 15th to June 15th, 2023). Female students from all school years attending health sciences (studies of medicine, dentistry and nursing) were included in the study. As dysmenorrhea is most common among women aged 15–25 years students were chosen for the study as the common proxy for young and healthy populations [ 5 , 6 ]. Before the study commenced, the sample size was calculated based on the number of female students attending the University (N = 323 respondents, confidence interval 95%, margin of error 5%, study power 95.3%). The study inclusion criteria were as follows: aged ≥18 years, complaining on dysmenorrhea at least once during the past 12 months, having primary dysmenorrhea and being a health sciences student fluent in the Serbian language. The study exclusion criteria were as follows: verified gynecological and/or psychiatric diseases, which, according to the literature, may be the cause of secondary dysmenorrhea (myoma, adenomyosis, endometriosis, anxiety, depression, etc.), declining participation or fulfilling less than 90% of the questionnaire. The recruitment of respondents was carried out on weekdays during regular compulsory theoretical and practical classes and in agreement with lecturers who were all very helpful and willing to allow the survey. Before being included in the study, student was thoroughly informed by the researchers about the signs and symptoms as well as the causes of dysmenorrhea and the purpose of the study. All students gave their signed consent for participation after which they were offered to fill-in a set of questionnaires in the paper form. Students filled-in the questionnaires alone at their seats which took up to 20 minutes. Researchers were present for all questions. The response rate was 83.3%. Students who declined participation had no specific differences from the others, but were generally not interested in taking surveys or felt tired and opted to make a 15 minutes break from lectures. Finally, we had to exclude 6 students as they filled in less than 90% of the questionnaire and 29 students who reported having conditions that might cause secondary dysmenorrhea. The study was approved by the Ethics Committee of the Faculty of Medicine, University of Pristina, temporarily settled in Kosovska Mitrovica (05.04.2023. Approval 09–799). The DSI is a 9-item scale that measures how dysmenorrheal symptom affects physical, mental and social activities of a woman. The items are scored from 1 (not at all) to 5 (very much). The scores given to the items are summed up and the final scale score is calculated as the mean of item scores (range 1–5). The higher the final score of the scale, the greater the impact of dysmenorrhea on the mentioned daily activities. The DSI was developed as a one-factor construct in English language and validated in the United States for use among women aged 14–42 years. It can be administered in paper or electronic form. Self-administration is preferable, but it can also be used in interviews. Original testing and previous validations showed very good psychometric properties of DSI making it useful for both clinical work and research [ 17 , 18 ]. The Depression, Anxiety and Stress Scale – 21 items (DASS 21) is one of the most reliable and commonly used instruments designed to assess the severity of general psychological distress and assess negative emotional states in clinical and non-clinical settings. It is a self-reported questionnaire that comprises 21 items/statements divided into three domains (depression, anxiety and stress) each with 7 items/statements. The statements refer to the period of the previous week. Respondents rate each statement from 0 (not at all) to 3 (mostly or almost always). The cut-off values based on the original validation study, and recommended in the scoring instructions, for the severity of the mental condition are: ≥ 10 for the depression scale, ≥ 8 for the anxiety scale and ≥15 for the stress scale. Finally, the original scores are multiplied by two to obtain a total DASS 21 score. Higher scores indicate a more severe disorder [ 21 , 22 ]. The license to use the DSI questionnaire was obtained from ePROVIDE™, Mapi Research Trust, Lyon, France (No 2211755, 18.08.2022.) [ 18 ]. The DSI was translated according to the internationally accepted methodology to generate a version that was semantically and conceptually as close as possible to the original [ 23 ]. Translation of the original English DSI to Serbian language (“forward translation”) was performed by two independent translators (study authors) native Serbian speakers fluent in English language. The “backward translation” (from Serbian back to English) was completed by the third translator (native English speaker fluent in Serbian language) who was blinded to the original questionnaire. Finally, translators discussed all items to generate a version which would be the most appropriate for the cultural environment of Serbia. The final Serbian version of the DSI was tested on 10 female students to check if any of the items were incomprehensible, confusing or culturally inappropriate. As there were no remarks on clarity and understanding of items and as there were no suggestions to include additional items, the final version was generated and applied in this study. Methods of descriptive and analytical statistics (number, percent, mean value, standard deviation – SD and χ2 test) were used to briefly illustrate the study population. As this study is a part of a larger investigation, description of the study sample was previously performed in SPSS (version 21 IBM, USA) program, while all validity analyses for this study were performed in JASP (version 0.19.3 University of Amsterdam) statistical software. To describe DSI questionnaire, we analyzed minimal and maximal values, mean and standard deviation. Data distribution was investigated by Kolmogorov-Smirnov test (p > 0.05 indicates normal distribution) and skewness (if data do not weight toward score extremities skewness value should between −1 and 1). Moreover, Mardia’s test was also done to assess multivariate normality [ 23 ]. To examine the validity evidence based on internal structure of the Serbian DSI version we performed exploratory factor analysis (EFA) and the confirmatory factor analysis (CFA). For these analyses the sample was divided in two equal (n = 175) random groups (one as EFA sample and one as CFA sample) as suggested for confirmation of EFA findings by CFA on a separate sample and to avoid testing the data against itself [ 23 , 24 ]. For obtaining reliable results of questionnaire validation it is commonly recommended to include 5–10 participants per item [ 24 ]. As the DSI had 9 items the sample size of 175 students per group was considered as adequate. The Kaiser-Meyer-Olkin (KMO) test and Bartlett’s test of sphericity were analyzed to assess the adequacy of sampling (KMO values above 0.7) and to determine if the correlations between variables are significant enough for factor analysis (significant p-value in Bartlett’s test) [ 23 , 24 ]. In EFA minimum residuals factoring method was applied to extract the factors. Factor loadings (correlations between the questionnaire items and extracted factors) were analyzed using the cut-off points of 0.40. If eigenvalues of the factor are above 1.0 the factor is significant. Additionally, parallel analysis was performed to ensure that the selection of latent factors is properly conducted. Finally, communality indices (CI – the sum of squared factor loadings) of questionnaire items were evaluated. Item CI should be ≥ 0.4 for the item to be kept as the part of the questionnaire [ 23 , 24 ]. In the CFA, as the model goodness-of-fit estimators we assessed goodness of fit index (GFI), comparative fit index (CFI), Tucker-Lewis Index (TLI), normative fit index (NFI), Non-Normed Fit Index (NNFI), Parsimony Normed Fit Index (PNFI), McDonald fit index (MFI), Relative Fit Index (RFI), root mean square error of approximation (RMSEA) and SRMR (Standardized Root Mean Square Residual). The Unweighted Least Squares (ULS) estimator was chosen for the analysis as it optimally corresponded with our non-normally distributed data in a limited sample. For the model to be adequate values of RMSEA and SRMR should be ≤ 0.08 (with upper limit of the confidence interval below 0.1) while other indices should optimally be ≥ 0.90. Higher values of PNFI indicate better model fit [ 23 , 24 ]. Internal consistency of the Serbian DSI version was evaluated by Cronbach’s alpha and McDonalds Omega coefficients. Alpha coefficient is based on the average inter-item correlation and relies on strict assumptions that all items load equally on the underlying factor. Omega coefficient is based on a factor analysis model. It accounts better for multidimensionality and is therefore considered to be more accurate. For both coefficients satisfactory values are above 0.7 [ 23 ]. Hotelling T–square test (HT2) shows whether or not there is a significant difference between obtained mean score values of all DSI items together and the hypothetic case in which items have equal scores [ 23 ]. Discriminating characteristics of the questionnaire items were tested by Corrected Item – Total Correlation (CI–TC) analysis. This analysis showed the relationships of one item with the score of remaining questionnaire items. An item is considered as adequate part of the questionnaire if CI–TC is ≥ 0.40 [ 23 ]. The convergent validity was investigated by Spearman’s correlation coefficient. Various literature data demonstrated the significant association of dysmenorrhea, stress and depression [ 15 , 20 ]. Therefore, the final DSI score was correlated with the scores of DASS 21. DASS 21 is established and widely used questionnaires for evaluation of different psychological disturbances that can occur during menstrual cycle of some women [ 22 , 25 ]. Finally, discriminant analysis was assessed by comparing the DSI scores between students with mild and severe dysmenorrhea to establish the potential of DSI to differentiate between patient groups [ 23 ]. Mild dysmenorrhea was considered if the pain was reported to be manageable and not lasting longer than the first 2–3 days of the cycle. Patients have severe dysmenorrhea if the intense and prolonged pain is followed by systemic symptoms causing interference with daily activities [ 1 , 3 ].