Development of an endometriosis self-care behaviors scale: a psychometric study

This was a methodological study. The study was carried out in line with the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) checklist [ 26 ]. In the relevant literature, for scale development studies, it is recommended that the sample size be at least 5 or preferably 10 times the number of items in the scale to be tested and/or that the sample include at least 200 participants for factor analysis. Conducting exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) in different samples is also recommended [ 22 , 27 , 28 ]. Based on these recommendations, the sample size of this study was determined to be 400 in total, including 200 participants in the group whose data would be used for EFA and 200 in the group whose data would be used for CFA. The sample of the study consisted of women who were diagnosed with endometriosis by a specialist physician, were 18–49 years old, had endometriosis-related pain symptoms, had been followed up for at least six months with this diagnosis, did not have any medical or gynecological problem other than endometriosis, could speak and understand Turkish, and agreed to participate in the study. Pregnant women were excluded. Data were collected using a “Participant Description Questionnaire” and the “Endometriosis Self-Care Behaviors Scale”. The form was developed by the researchers based on the relevant literature to collect information on the sociodemographic, obstetric, gynecological, and medical characteristics of the participants [ 6 , 9 , 12 , 13 , 29 ]. It included 19 questions. ESCBS was developed to evaluate the self-care behaviors of women with endometriosis. It has a 5-point Likert-type scoring system with the response options of “Never = 1”, “Rarely = 2”, “Sometimes = 3”, “Often = 4”, and “Always = 5”. There is no inversely scored item in the scale. Higher scores are interpreted to indicate better self-care behaviors in women with endometriosis. In line with the recommendations of the relevant guidelines regarding scale development and validation, this study was carried out in two phases: (1) item development and pilot study and (2) construct validity and reliability testing [ 22 , 28 ]. This phase consisted of four steps. The first step involved the clear identification of the construct that was intended to be measured and the creation of an item pool for this purpose. The item pool was developed based on data obtained from qualitative interviews and a comprehensive literature review, both guided by Orem’s Self-Care Model as the theoretical framework. The qualitative interviews were conducted with six women diagnosed with endometriosis using a semi-structured interview form, which included the open-ended question: ‘What self-care behaviors and coping strategies do you use to alleviate your endometriosis-related complaints?’ The interviews were audio-recorded and analyzed using content analysis. The literature review was conducted in Google Scholar, PubMed, and Web of Science databases using the keywords “endometriosis”, “self-care”, “self-care behaviors”, and “scale” in both Turkish and English. The review included systematic reviews, quantitative studies, clinical guidelines [ 6 , 7 , 12 , 13 , 15 , 20 , 21 , 29 – 40 ], and scale development studies [ 41 – 43 ]. Based on the findings from the qualitative interviews and literature review, the items were evaluated in line with Orem’s Self-Care Model and categorized under universal, developmental, and health deviation self-care requirements, resulting in a draft item pool consisting of 33 items. In the second step, the form of measurement was chosen. Likert-type measurements are frequently used as a form of measurement, and 5-point scales are considered the most suitable options [ 22 , 44 ]. For this reason, a 5-point Likert-type scoring system (1 = never, 5 = always) was preferred in this study. The third step involved the assessment of the items by experts in terms of their capacity to measure the intended variable, content validity, and comprehensibility. In this process, the draft scale form was first examined by an expert in the field of Turkish Language and Literature, and statements that could have been misunderstood were corrected. After this, feedback was obtained from 10 experts, including seven faculty members in obstetrics and gynecology nursing, one faculty member in psychiatric nursing (who had been diagnosed with endometriosis), one faculty member in nutrition and dietetics, and one physiotherapist. All faculty experts were determined to have at least seven years of experience in their respective fields, had prior involvement in or training on scale development, and held academic titles ranging from Assistant Professor to Professor. The physiotherapist reported having approximately eight years of experience and working specifically with women experiencing pelvic pain. The “Endometriosis Self-Care Behaviors Scale Draft – Expert Opinion Form” was was sent to the experts via email. The experts were asked to rate each item in the draft scale form in terms of its capacity to measure the intended variable (1 = not suitable, 2 = requires major revision, 3 = suitable, requires minor revision, 4 = highly suitable) and to provide additional suggestions for items they deemed necessary. To resolve any disagreements among the experts, the score distributions and comments for each item were reviewed by the researchers. Based on the experts’ ratings, the Content Validity Ratio (CVR) and Content Validity Index (CVI) were calculated by a biostatistics expert. It was stated that for 10 experts, the CVR value needs to be at least 0.80 [ 45 ]. Accordingly, eight items with a CVR below 0.80 were removed from the draft scale, and four items were merged into two. When necessary, follow-up email correspondence was conducted with the experts to clarify their suggestions, and consensus was reached on the final draft of the scale consisting of 23 items. This revised form was evaluated again by 10 different experts, and its CVI values were found to be greater than 0.80. The fourth step was the pilot implementation step. For pilot studies, the generally recommended sample size is 30–100 participants [ 46 ]. To confirm the comprehensibility of the scale items in this study, a pilot implementation was made with the participation of 30 women. Following the pilot implementation, the item “I regularly use the drugs prescribed by my doctor in the way they are prescribed” in the draft form was removed because it was not applicable to everyone in the target audience, and the number of items in the draft form became 22. The construct validity of the scale was tested by EFA and CFA. For these analyses, a table of random numbers was created in Microsoft Excel by an expert statistician. The participants were assigned to the numbers corresponding to the groups of the sample (1: EFA group; 2: CFA group), and the relevant analyses were carried out. Before factor analyses, to determine whether the data were suitable for factor analysis, the Kaiser–Meyer–Olkin (KMO) Test and Bartlett’s Test of Sphericity were performed. For a dataset to be suitable for factor analysis, its KMO value must be greater than 0.5, and the result of Bartlett’s test of sphericity must be significant ( p  < 0.05) [ 47 ]. After the satisfaction of these criteria, EFA was conducted. According to the information in the literature, in EFA, a multi-factor construct should have a variance explanation ratio of at least 40%, each of its factors should have eigenvalues of at least 1, and its items have factor load values of at least 0.50 [ 22 , 47 – 49 ]. After the EFA, CFA was carried out. In CFA, among model fit indices, the ratio of the chi-squared value to the degrees of freedom (χ 2 /df) is considered to indicate excellent model fit when it is ≤ 2. When the Goodness of Fit Index (GFI), Tucker Lewis Index (TLI), Incremental Fit Index (IFI), and Comparative Fit Index (CFI) values are ≥ 0.90, a model is considered to show an acceptable fit [ 50 , 51 ]. Root Mean Square Error of Approximation (RMSEA) and Standardized Root Mean Square Residual (SRMR) values of ≤ 0.05 are accepted to indicate excellent model fit, while values in the range of 0.05–0.08 are considered acceptable [ 50 ]. The reliability of ESCBS was analyzed based on Cronbach’s alpha internal consistency coefficient (α), item-total score correlations, and the test–retest reliability analysis method. According to the recommendations of DeVellis and Thorpe, coefficients of α < 0.60 are “unacceptable”, whereas values of 0.60 ≤ α < 0.65 are considered “undesirable”, values of 0.65 ≤ α < 0.70 are “minimally acceptable”, values of 0.70 ≤ α < 0.80 are “good”, values of 0.80 ≤ α < 0.90 are “very good”, and values of α ≥ 0.90 are “excellent” [ 22 ]. In addition to this, if a new scale is being developed, values of α ≥ 0.60 are accepted as “sufficient” [ 50 ]. In item-total score correlation analyses, correlation coefficients of ≥ 0.30 are considered to indicate good reliability. However, if the correlation coefficient of an item is smaller than 0.30, its effect on the α value must be evaluated [ 52 , 53 ]. In test–retest reliability analyses, the general view is that the coefficient of correlation between two measurements should be at least 0.70 [ 50 , 54 ]. The data were collected at the endometriosis outpatient clinic of a research and training hospital between March 2023 and April 2024. The data collection process was carried out by a research assistant (HAT) who was part of the study team and well-acquainted with the study methodology. The research assistant had previous experience in various academic research projects and was knowledgeable in the administration of measurement instruments, protection of participants’ rights, adherence to ethical principles, and data confidentiality. This expertise contributed to ensuring consistency during the data collection process and minimizing potential errors. At this stage, the researcher explained the objective and procedures of the study to women who visited the outpatient clinic for endometriosis-related follow-ups and met the inclusion criteria. Written consent was obtained from the women who agreed to participate. The contact information of the women was saved so that they could be contacted later for the retest. Then, the “Participant Identification Questionnaire” and the “Endometriosis Self-Care Behaviors Scale—Draft Form” were given to the women, and the women were informed about how to fill out these forms. All questions of the participants were answered by the researcher in the data collection process. It took about 10–15 min for each participant to fill out the data collection forms. After the data collection forms were received by the researcher, any incomplete or incorrectly marked items were immediately reviewed with the participant and corrected. Prior to statistical analyses, the dataset was examined by a biostatistician, and no logically invalid entries or outliers were identified. Thus, data integrity and the reliability of the analyses were ensured. The data collection process included 410 women in total. As seven of these women did not want to participate in the study, and three were unable to speak and understand Turkish, the study was completed with 400 women. To determine the test–retest reliability of ESCBS, the scale was administered again to 55 participants who were randomly selected from within the sample two weeks after the first data collection step. Before starting the study, permission was obtained from the administration of the faculty of health sciences where the study was conducted and study approval from the non-interventional ethics committee (ethics committee approval number: 30.03.2023/52). The study was carried out in compliance with the principles of the Declaration of Helsinki, written permission was received from the outpatient clinic where the study would be conducted before starting the study, and the participants gave consent after being informed about the study. Data were analyzed using the SPSS for Windows Version 23.0 statistical software package (SPSS Inc., Chicago, IL, USA). Descriptive data were presented as mean ± standard deviation, frequency, and percentage. The normality of the data distribution across groups was assessed using the Shapiro–Wilk test and by examining skewness and kurtosis coefficients within the range of −1.5 to + 1.5 [ 55 ]. For comparisons between two groups with normally distributed data, the Independent Samples t-test was used. Pearson’s Chi-Square test and Fisher’s Exact test were applied for comparisons of categorical variables. For EFA, Principal Component Analysis with Varimax rotation was employed. In addition, CFA was performed using the AMOS 23 software package to verify the original factor structure of the scale. Reliability was assessed with Cronbach’s alpha, and the intraclass correlation coefficient was calculated for test–retest results. Significance was accepted at p < 0.05.

The sociodemographic, obstetric, and gynecological characteristics of the participants are presented in Table  1 . There was no statistically significant difference between the groups in terms of the variables of age, education level, employment status, income level, marital status, age at menarche, menstrual cycle, number of pregnancies, endometriosis diagnosis duration, endometriosis symptoms, receiving treatment for endometriosis, smoking, alcohol consumption, regular exercise status, and dietary preferences ( p  > 0.05; Table  1 ). Table 1 Sociodemographic, obstetric, and gynecological characteristics of the participants ( n  = 400) Characteristics EFA group ( n  = 200) CFA group ( n  = 200) Test value p X̄ ± SD X̄ ± SD Age, years 32.80 ± 7.20 32.89 ± 7.53 −0.129 0.897 t Age of menarche, years 13.03 ± 1.56 13.03 ± 1.47 −0.001 0.999 t Number of pregnancies* 1.95 ± 1.00 1.89 ± 1.10 0.351 0.726 t Endometriosis diagnosis duration, years 5.00 ± 4.93 5.21 ± 4.74 −0.451 0.652 t n % n % Education level Primary school 22 11 18 9.0 2.981 Secondary school 12 6.0 16 8.0 0.562 F High school 59 29.5 50 25.0 University or above 107 53.5 116 58.0 Employment Employed 110 55.0 109 54.5 0.010 0.920 χ2 Not employed 90 45.0 91 45.5 Income level Low 45 22.5 44 22.0 0.044 0.978 χ2 Medium 125 62.5 127 63.5 High 30 15.0 29 14.5 Marital status Married 111 55.5 105 52.5 0.362 0.547 χ2 Single 89 44.5 95 47.5 Menstrual cycle Regular 135 67.5 126 63.0 0.772 0.380 χ2 Irregular 65 32.5 74 37.0 Symptoms of endometriosis** Dysmenorrhea 193 96.5 190 95.0 0.553 0.457 χ2 Chronic pelvic pain 167 83.5 169 84.5 0.553 0.457 χ2 Dyspareunia 126 63.0 125 62.5 0.011 0.918 χ2 Dyschezia 99 49.5 101 50.5 0.040 0.841 χ2 Dysuria 75 37.5 73 36.5 0.043 0.836 χ2 Receives endometriosis treatment Yes* 136 68.0 135 67.5 0.011 0.915 χ2 No 64 32.0 65 32.5 Smoking status Smoker 79 39.5 88 44.0 0.833 0.362 χ2 Non-smoker 121 60.5 112 56.0 Consumes alcohol Yes 33 16.5 23 11.5 2.076 0.150 χ2 No 167 83.5 177 88.5 Regular exercise status Doing 47 23.5 44 22.0 0.128 0.720 χ2 Not doing 153 76.5 156 78.0 Dietary preferences** Carbohydrate-rich diet 119 59.5 110 55.0 0.827 0.363 χ2 Plant-based diet 86 43.0 70 35.0 2.690 0.101 χ2 Protein-rich diet 84 42.0 80 40.0 0.165 0.684 χ2 Fast-food-based diet 27 13.6 32 16.1 0.497 0.481 χ2 X̄ Mean, SD Standard deviation, χ2 Chi-square test, F Fisher’s exact test, t Independent samples t-test * The average number of pregnancies was calculated only for women with a history of pregnancy (AFA group n  = 83, DFA group n  = 74) ** Since the participants chose more than one answers, n was based on the individuals answering the question and it was multiplied Sociodemographic, obstetric, and gynecological characteristics of the participants ( n  = 400) X̄ Mean, SD Standard deviation, χ2 Chi-square test, F Fisher’s exact test, t Independent samples t-test * The average number of pregnancies was calculated only for women with a history of pregnancy (AFA group n  = 83, DFA group n  = 74) ** Since the participants chose more than one answers, n was based on the individuals answering the question and it was multiplied The KMO coefficient of ESCBS was 0.74, and the result of the Bartlett’s test (χ 2 : 868.709, df: 136) was significant ( p  < 0.001). The EFA results of the scale are shown in Table  2 . As a result of the principal component analysis, 5 items with factor load values smaller than 0.40 ( Item 2. I sleep 7–9 h a day, Item 8. I limit the consumption of foods that raise estrogen (female sex hormone) secretion (e.g., soybeans and soy products), Item 12. I apply a warm compress to cope with endometriosis-related pain, Item 14. I can perform my daily chores (housework and/or job), and Item 20. I use methods to help me cope with stress (e.g., emotional support, hobbies, talking to a loved one) ) were removed from the analyses, and the number of scale items decreased from 22 to 17. It was determined that these 17 items were gathered under 4 factors, and their factor loads were in the range of 0.52–0.81. The factors of the scale explained 53.1% of the total variance in the measured construct, and the lowest eigenvalue was 1.8 (Table  2 ). Table 2 Exploratory factor analysis of ESCBS Factors ESCBS items Factor loading Variance Explanation ratio Eigenvalue Item 1. I know what endometriosis is and monitor changes. 0.61 Factor 1: Disease awareness Item 3. I attend my doctor’s follow-ups regularly. 0.78 Item 4. I accept/try to manage complaints that I experience due to endometriosis. 0.58 12.8 2.2 Item 5. I follow sources of information about endometriosis (e.g., watching health-related shows, reading medical brochures). 0.65 Item 6. I seek counseling from expert healthcare personnel if my endometriosis-related complaints are not resolved or if I cannot get pregnant. 0.52 Factor 2: Diet Item 7. I limit my consumption of foods that I notice increase my digestive complaints (e.g., wheat and derivatives, sugar and foods with added sugar, red meat). 0.76 Item 9. I prefer having steamed, roasted, or grilled foods rather than fried or broiled food. 0.77 Item 10. I limit my consumption of ready and packaged foods (foods containing additives and preservatives). 0.81 13.6 2.3 Item 11. I consume 2-4 portions of vegetables and 2-3 portions of fruit per day. 0.53 Factor 3: Physical activity and exercise Item 13. I perform 45–60 minutes of walking or exercise 3–4 times per week to help cope with my illness. 0.73 Item 15. I actively participate in social activities (e.g., friendly gatherings, movies, theater). 0.72 10.4 1.8 Item 16. I use relaxation techniques to cope with endometriosis-related pain (e.g., yoga, breathing exercises, and massage). 0.68 Factor 4: Psychosocial and physical support Item 17. I rest by sitting/lying down during the day to alleviate endometriosis-related pain. 0.71 Item 18. I get help from people around me when I am unable to perform my daily activities due to pain. 0.74 Item 19. I receive the support of my close circle or an expert when I feel concern and stress related to endometriosis. 0.68 16.3 2.8 Item 21. I share my thoughts and feelings about endometriosis with others. 0.66 Item 22. I benefit from the experiences of women with endometriosis by sharing my problems with them. 0.63 ESCBS  Endometriosis Self-Care Behaviors Scale Exploratory factor analysis of ESCBS ESCBS  Endometriosis Self-Care Behaviors Scale In the CFA results of ESCBS, χ 2 /df was found to be 1.46. The other goodness-of-fit index values were GFI: 0.92, TLI: 0.89, IFI: 0.91, CFI: 0.91, RMSEA: 0.05, and SRMR: 0.07. Accordingly, the 4-factor construct was confirmed. The path diagram of the confirmed model is shown in Fig.  1 . Fig. 1 Confirmatory factor analysis results of ESCBS Confirmatory factor analysis results of ESCBS The Cronbach’s alpha internal consistency coefficient (α), which was calculated to test the reliability of ESCBS, was 0.79. The Cronbach’s alpha internal consistency coefficients of the subscales were calculated as 0.65 for disease awareness, 0.71 for diet, 0.63 for physical activity and exercise, and 0.77 for psychosocial and physical support. The corrected item-total score correlation coefficients of the scale varied between 0.17 and 0.54 (Table  3 ). The overall test re-test reliability was found to be 0.71, which showed a statistically significant agreement. Table 3 Subscales and scales reliability r α a α Disease awareness Item 1 0.17 0.79 0.65 0.79 Item 3 0.19 0.78 Item 4 0.30 0.78 Item 5 0.53 0.76 Item 6 0.36 0.77 Diet Item 7 0.40 0.77 0.71 Item 9 0.30 0.78 Item 10 0.33 0.77 Item 11 0.27 0.78 Physical activity and exercise Item 13 0.43 0.77 0.63 Item 15 0.30 0.78 Item 16 0.36 0.77 Psychosocial and physical support Item 17 0.40 0.77 0.77 Item 18 0.41 0.77 Item 19 0.50 0.76 Item 21 0.49 0.76 Item 22 0.54 0.76 r corrected ıtem-total correlation , α Cronbach’s alpha for total scale , α a Cronbach’s alpha if item deleted Subscales and scales reliability r corrected ıtem-total correlation , α Cronbach’s alpha for total scale , α a Cronbach’s alpha if item deleted

ESCBS was determined to be a valid and reliable measurement instrument that could be used to evaluate the self-care behaviors of women with endometriosis in Turkey. It is a scale consisting of 17 items and four dimensions. The minimum and maximum total scores that are possible on the scale are 17 and 85. As the total score from the scale increases, self-care behaviors in women with endometriosis also increase. In this context, future research is recommended to re-test the validity and reliability of the ESCBS in different countries and larger samples. It is also suggested that the scale be used both in clinical practice and in scientific studies to identify the self-care behaviors of women with endometriosis, evaluate the effectiveness of these behaviors, and plan education and counseling services in this direction.

In Turkey, there is no standardized measurement instrument evaluating the self-care behaviors of women with endometriosis. The purpose of this study was to develop a measurement instrument that is suitable for Turkish culture, valid, and reliable in the measurement of the self-care behaviors of women with endometriosis. In the study, women in the EFA and CFA groups were found to be homogeneously distributed in terms of sociodemographic characteristics such as age, educational level, employment status, income level, marital status, smoking, alcohol use, regular exercise, and dietary preferences; obstetric characteristics such as total number of pregnancies; and gynecological characteristics such as age at menarche, menstrual cycle, endometriosis diagnosis duration, endometriosis symptoms, and receiving treatment for endometriosis (Table  1 ). This result is important for ensuring the comparability of the factor structures obtained from the analyses of the scale and for supporting the validity and reliability of the scale. KMO and Bartlett’s tests were carried out before determining the factor structure of the scale. The KMO coefficient and the significant result of the Bartlett’s test showed that the dataset and sample were suitable for factor analysis. The construct validity of the scale was tested by EFA and CFA. EFA allows researchers to determine the number and categories of factors constituting a scale [ 47 ]. In this study, following the EFA, five items were removed because they had factor loads lower than the predetermined threshold. After the removal of items, the remaining 17 items were grouped into four factors: “Disease Awareness”, “Diet”, “Physical Activity and Exercise”, and “Psychosocial and Physical Support” and it was determined that the items explained more than half of the total variance in the overall construct, and the factor loads and eigenvalues were greater than the predetermined thresholds (Table  2 ). These results demonstrated the construct validity of the scale. Moreover, the factor structure derived from the scale, which was based on the Self-Care Model, was found to be consistent with theoretical expectations. Specifically, the “Diet” and “Physical Activity and Exercise” factors reflected behaviors necessary for maintaining daily life and corresponded to Orem’s universal self-care requisites. The “Psychosocial and Physical Support” factor encompassed the pursuit of physical, social, and emotional support to adapt to a chronic illness process, aligning with Orem’s developmental self-care requisites. Finally, the “Disease Awareness” factor included behaviors such as attending regular medical check-ups, obtaining information about the illness, and seeking professional counseling when needed, directly addressing Orem’s health-deviation self-care requisites. Therefore, it can be concluded that the four factors obtained are in comprehensive alignment with the framework of self-care requisites defined in Self-Care Model, supporting the theoretical validity of the scale. Following the EFA, CFA was conducted to test the model, and model fit indices were evaluated [ 47 ]. Striving to achieve the best possible value for each fit index may lead to an artificially confirmed model. Therefore, if the items and factors form a meaningful whole from the researcher’s theoretical perspective, the decision should be made accordingly [ 56 ]. According to the CFA results, the χ 2 /df and RMSEA values indicated an excellent fit, while the GFI, IFI, CFI, and SRMR results indicated an acceptable fit. The TLI value (0.89) was found to be only 0.01 below the recommended threshold of 0.90. It has been noted that TLI is particularly sensitive to sample size and may underestimate model fit in samples smaller than 200. Therefore, even when other fit indices indicate good fit, TLI may yield lower values. In this context, some researchers consider TLI values of 0.80 and above as indicative of marginally acceptable fit [ 57 ]. In our study, the CFA was conducted with a sample of 200 women with endometriosis, which may explain why the TLI value was borderline compared to other fit indices. Nevertheless, the CFA results demonstrated that the four subdimensions generally exhibited acceptable levels of model fit indices (Fig.  1 ). The reliability of a Likert-type scale is often tested using α [ 50 ]. In this study, the α value of ESCBS was found to indicate good reliability according to previously reported metrics [ 22 ]. The α values of the dimensions of the scale were acceptable for “Disease Awareness”, sufficient for “Physical Activity and Exercise”, and good for “Diet” and “Psychosocial and Physical Support” [ 22 , 50 ]. The variations in the α values of the dimensions of the scale were considered to originate from the fact that they included different numbers of items. Another method of measuring reliability is item-total score correlation analysis. In this study, according to the item-total score correlation analysis results, the correlation coefficients of 14 items of ESCBS indicated good reliability [ 52 , 53 ]. However, the correlation coefficients of three items were < 0.30. Because no significant change was foreseen in α in case any of these items were removed, none of them was removed [ 52 , 53 ]. Considering all these results, it can be argued that the items of the scale had discriminatory power, and they were reliable (Table  3 ). Test–retest reliability refers to the ability of a measurement instrument to provide consistent results in different implementations, that is, time-invariance [ 50 ]. There was a statistically significant and very high rate of agreement between the first and second implementations of ESCBS in this study. This demonstrated that ESCBS could always make consistent measurements, and it was reliable in this context.

The main limitation of this study was the lack of sufficient evidence-based research on self-care behaviors related to endometriosis. Therefore, the scale could only determine the frequency of self-care behaviors. In addition, the study was conducted in a single center. Thus, the results are valid only for women with endometriosis at the center where the study was carried out and cannot be generalized.

Endometriosis is a benign chronic disease that is characterized by the settlement and growth of endometrial tissue, which is normally supposed to be in the uterine cavity, outside the uterine cavity [ 1 ]. It is reported that an estimated 10% (190 million) of women of reproductive age worldwide are affected by endometriosis [ 1 ]. In Turkey, an epidemiological study indicated that 18.3% of women of reproductive age have endometriosis [ 2 ].The etiology of the disease is not yet completely known. However, it has been reported that its risk factors include genetic, hormonal, and environmental factors, as well as risky lifestyle behaviors ( e.g., unhealthy diet (e.g., alcohol consumption, excess consumption of trans fats and red meat) and lack of regular exercise) [ 3 , 4 ]. Pain symptoms (dysmenorrhea, pelvic pain, dyspareunia, dysuria, dyschezia) and infertility symptoms are frequently seen in endometriosis [ 5 ]. These symptoms may affect the social lives, emotional health, and quality of life of women negatively [ 3 ]. To alleviate endometriosis symptoms and increase quality of life in this process, medical interventions include pharmacological (analgesic, hormonal treatment) and/or surgical treatment options [ 1 ]. However, the pain complaints of many women may persist despite these treatments, and their quality of life may be affected adversely. Pharmacological treatment may also have side effects, and 10–40% of women may quit treatment. Surgical treatment may also lead to complications, and the disease and its symptoms may recur. For all these reasons, in addition to treatment, women need self-care strategies to manage their symptoms [ 6 , 7 ]. According to Dorothea Orem, self-care is a process that involves the personal practices of a person to maintain their health, personal development, and welfare and manage situations such as chronic diseases [ 8 ]. Self-care behaviors in chronic diseases theoretically refer to the behaviors of maintaining, monitoring, and managing self-face [ 9 ]. Self-care maintenance behaviors are those that protect physical and emotional stability (e.g., yoga or music) or prevent the exacerbation of the disease (e.g., taking medication as prescribed). Self-care monitoring behaviors involve the person’s self-observation in terms of changes in signs and symptoms. Self-care management behaviors refer to responses given to signs and symptoms when they arise (e.g., changing activity levels) [ 9 , 10 ]. These behaviors can contribute to a rise in the quality of life of individuals with chronic diseases, higher knowledge and awareness, lower stress levels, the acceptance of the disease, the effective management of the disease, and the reduction of healthcare costs [ 9 , 11 ]. For these reasons, women with endometriosis a chronic illness may turn to self-care behaviors such as receiving medical and psychosocial support, a healthy diet, physical activity/exercise, relaxation techniques (massage, yoga, breathing exercises), warm compress, sufficient sleep, and rest [ 12 – 19 ]. According to the literature, a randomized controlled trial conducted by Farshi et al. demonstrated that self-care counseling reduced anxiety levels and improved quality of life in women with endometriosis [ 12 ]. In a quasi-experimental study by Kamal Helmy et al., a nursing intervention program focusing on lifestyle modifications (such as healthy dietary habits, physical activity, and stress management) was found to be effective in increasing women’s knowledge levels and reducing symptoms associated with endometriosis, including depression, anxiety, fatigue, and pain [ 20 ]. Similarly, a quasi-experimental study by Mohamed et al. reported that instructional nursing strategies reduced disease-related symptoms and improved knowledge levels and self-care behaviors in women with endometriosis [ 21 ]. Among the studies directly or indirectly related to self-care behaviors, only one was found to implement a systematic counseling program based on the Self-Care Model. Furthermore, the studies assessing self-care behaviors did not employ measurement instruments with established validity and reliability. In this context, there is a recognized need for further research to evaluate the effectiveness of self-care behaviors in women with endometriosis, particularly through the development of theoretically grounded instruments with demonstrated psychometric properties. However, in the literature review, no measurement instrument designed for measuring self-care behaviors in endometriosis could be encountered. The lack of such a measurement instrument may lead to the adoption of arbitrary measurement approaches, and thus, the collection of erroneous data (and results). This situation brings about the need for researchers to develop measurement instruments suitable for their target population [ 22 ]. Hence, the development of a measurement instrument that will evaluate the self-care behaviors of women with endometriosis is highly important in terms of the objective assessment of the effectiveness of these behaviors in disease management. In the process of developing a research instrument, grounding it in a theoretical framework or model is crucial for establishing scientific validity. Dorothea Orem, one of the pioneers who introduced the concept of self-care behavior into the nursing literature, is widely recognized for her Self-Care Model, which is considired one of the most comprehensive frameworks in this field [ 23 ]. Accordingly, the scale developed in our study was constructed based on Self-Care Model. According to the model, self-care requirements encompass all actions that individuals must undertake to prevent illness and promote health. These self-care requirements may vary throughout an individual’s lifespan. Within this framework, self-care requirements are categorized into three groups: universal, developmental, and health deviation requirements. Universal self-care requirements refer to those essential for maintaining the integrity of human structure and function and are associated with basic life processes. Developmental self-care requirements arise during different stages of the life cycle. Health deviation self-care requirements occur in situations of illness, injury, or disability [ 24 , 25 ]. In this context, endometriosis is considered a health deviation, requiring individuals to develop specific self-care behaviors to maintain comfort and carry out daily functions. The scale was developed to assess such behaviors and is based on Orem’s categories of universal, developmental, and health deviation self-care requirements. In this study, it was aimed to develop the Endometriosis Self-Care Behaviors Scale and test its validity and reliability.