This will be a randomized controlled trial with 3 groups: a control group, a behavioral intervention (BI) group, and a behavioral intervention and massage (BIM) group. The same number of people will be randomly distributed in each group with a 1:1:1 allocation ratio, so that the 3 groups are homogeneous for age, sex, and constipation characteristics. Data collection will be between 2024 and 2026.

The choice of primary care as the study setting reflects its central role in the early management and long-term monitoring of chronic constipation. This environment ensures high feasibility, as the intervention can be delivered using existing staff—nurses, physiotherapists, general practitioners, and nutritionists—and infrastructure, requiring minimal additional resources. Moreover, the intervention is designed to be easily integrated into routine care pathways, aligning with preventive care goals and enhancing patient self-management strategies within the primary care framework.

This study will recruit patients aged 18 to 75 years assigned to the primary care centers of the counties of l’Anoia and Bages in Catalonia, Spain.

The inclusion criteria are having been diagnosed with primary constipation using the Rome IV criteria [11] lasting for more than 3 months and understanding Catalan, Spanish, or English.

The exclusion criteria are having constipation secondary to neurogenic, metabolic, endocrine, or postoperative diseases; having constipation secondary to medication for other pathologies, the medication list for which can be found in Multimedia Appendix 1; having any type of open abdominal and/or anal wound, such as a recent abdominal scar or anal fissure; meeting any absolute contraindication criteria for the use of abdominal massage therapy, such as an unstable fracture requiring absolute rest and immobilization, pregnancy, or active oncological procedures, and having a cognitive, psychiatric, or neurological condition that, in the clinical judgment of the health care professional, significantly limits the individual’s capacity to provide informed consent or to participate meaningfully in the intervention and data collection procedures.

Calculations were based on published evidence suggesting that approximately 90% of patients in the control group would remain constipated at 3 months. We hypothesized that this proportion would decrease to 40% in the intervention groups (BI and BIM), corresponding to a 50% absolute difference. To detect this difference with 80% power and a 2-sided significance level of 5%, while allowing for a 10% dropout rate, 15 participants per group are required. With 3 groups, the total sample size will therefore be 45 participants in total. Recruitment will take place across the 2 participating centers (Anoia and Bages), with approximately 7 to 8 participants per group expected to be recruited at each center.

The sample will be selected (1) by means of a medical history review by nursing or medical personnel; if the health professional considers that the patient meets the criteria, they will refer the patient to the research physiotherapist; and (2) indirectly, by putting up posters in casals cívics (civic facilities) and pharmacies in the city. Anyone learning about the study this way can make an appointment with their health professional of reference (ie, nursing or medical staff) and discuss their interest in participating in the study. If the health care professional confirms that the patient meets the criteria, they will refer the patient to the research physiotherapist.

The randomization and allocation of patients will be performed by simple randomization using the specialized software RStudio (version 4.2.1; R Foundation for Statistical Computing). The distribution is expected to be homogeneous between groups. Randomization will be conducted by an independent researcher, and allocation will be concealed using sequentially numbered, opaque, sealed envelopes prepared in advance. This procedure ensures allocation concealment and minimizes selection bias.

The chosen sample size is based on feasibility and resource availability and is sufficient to detect large effect sizes. This study aims to assess the feasibility and potential impact of the intervention and to provide effect size estimates to guide future large-scale trials.

The research physiotherapist will inform the participants of the whole process and ask for informed consent, so that they can be randomized into the 3 study groups and their data can be included in the study database for later analysis. Participants will be informed that if the expected results are obtained, they will be offered the same treatment as the intervention group that obtained the best results.

The study was designed in accordance with the principles of the World Medical Association Declaration of Helsinki, as amended in 2013, and applicable regulations. The protocol was approved by the ethics committee of Jordi Gol Primary Care Research Institute (Barcelona, January 22, 2024; code 23/253-P).

The data controller and processor will be the Catalan Institute of Health. The database will be stored for a period of 10 years. The data obtained will not be disclosed to third parties by the research team. International transfers are not provided for. Security mechanisms are sufficient to prevent breaches of confidentiality.

Participants will be informed of the objectives and general aspects of this study and will be asked for informed consent. The informed consent form will specifically include the voluntary nature of participation, security measures, and the confidentiality of the data and its exclusive use for research purposes.

The European Data Protection Regulation 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and the free movement of such data and the Organic Law 3/2018 of 5 December on the Protection of Personal Data and guarantee of digital rights will be complied with at all times.

This protocol has been registered on ClinicalTrials.gov (NCT06359249). The final results will be submitted for publication in peer-reviewed journals and presented at relevant national and international conferences. In addition, findings will be shared with participating primary care centers and regional health authorities to support possible adoption into clinical practice. Participants will be informed of the study results through summary reports distributed via their primary care teams.

Participant enrollment concluded in August 2025, and data collection is ongoing and expected to continue until April 2026. The primary and secondary outcomes will be assessed at 3, 6, and 12 months after the intervention. Results will be analyzed using RStudio and reported in accordance with the Consolidated Standards Of Reporting Trials (CONSORT) guidelines for randomized trials.

The study’s findings will be disseminated through peer-reviewed publications and presentations at national and international conferences.

We will evaluate a set of indicators on constipation and other patient characteristics, as shown in Table 1. Outcomes will be assessed individually and at 5 different time points: before starting the intervention, on the same day of the intervention, 3 months after the intervention, 6 months after the intervention, and 12 months after the intervention. Data will be collected through standardized questionnaires to be completed independently by the participants.

The main variable will be the percentage of patients with constipation 3 and 6 months after the start of treatment for each group, a dichotomous qualitative variable. Prevalence will be estimated and analyzed using the χ² test.

The other variables will be reported as percentages and counts for categorical variables and through mean, median, deviation, and quartiles for continuous variables. In order to analyze relationships between the main variable and the sociodemographic or other explanatory variables, the χ² test will be used, and the relative risk will be estimated to compare the reduction between the two intervention groups with respect to the control group.

To evaluate the secondary variable, a continuous quantitative variable, ANOVA or the Kruskal-Wallis test will be used to determine differences between the 3 groups. To determine differences between pairs of groups, the Student t test or Mann-Whitney test will be used. Analyses will use 95% CIs, and the significance level will be set at 5%.

Due to the nature of the intervention, participant blinding is not feasible. However, to minimize potential bias in outcome assessment, data entry and statistical analysis will be performed by a researcher who is blinded to group allocation. This approach ensures objectivity in the interpretation of results, particularly for subjective outcome measures. All analyses will follow the intention-to-treat principle, including all randomized participants in the groups to which they were originally assigned. Missing data will be handled using multiple imputation under the assumption that data are missing at random. Statistical analysis will be performed with RStudio.

We anticipate that the structured rehabilitation program combining behavioral reeducation and abdominal massage will lead to a reduction in chronic constipation symptoms and laxative use at 3 and 6 months after the intervention. We also expect improvements in quality of life, particularly among participants receiving both behavioral education and massage therapy. Furthermore, we expect that both intervention groups will show improvements compared to the control group, but that the BIM group will experience greater improvements.

Constipation is often an underestimated condition, and the extent to which people experience hardship from it or its complications is not mentioned in primary care consultations. Reducing constipation will have a positive impact by reducing medicalization, alleviating complications, and decreasing the number of visits to primary care and specialized care. This will result in a better quality of life, reducing personal, physical, and social impacts. In addition, economic expenditures will be reduced due to the lowered use of the aforementioned resources. Therefore, the search for an effective therapy with fewer side effects, both to improve the quality of life of this part of the population and to reduce public health expenditure, should be a topic for research.

It is important to emphasize treating this condition in a logical, step-by-step manner. This includes the establishment of effective and simple conservative measures followed, if necessary, by pharmacological therapy, which is not always necessary. Concerningly, the general population often resorts to pharmacological therapy directly, often without having undergone conservative treatment [1].

The usual treatment for constipation is a reminder of healthy habits, including proper nutrition, hydration, physical activity, and use of laxatives, but these reminders are part of a very short consultation time, often not exceeding 5 to 7 minutes. There is little evidence on other possible conservative techniques, which include lifestyle changes, abdominal massage therapy, anal biofeedback, acupuncture, and dilators [32-39]. This research project guides new multidisciplinary treatments based on a change of habits and a more global approach to health, empowering the patient. In addition, there is the option of abdominal massage, a technique that is less harmful and invasive, less expensive, and self-performed by patient themselves to relieve the symptoms caused by constipation.

A key strength of this trial is its pragmatic design, making it well-suited for real-world implementation within the primary care system. The use of validated instruments (the Rome IV criteria, Bristol scale, CVE-20, and IPAQ) ensures reliable outcome measurement. Moreover, the multidisciplinary and participatory nature of the intervention promotes patient empowerment and supports long-term behavior change.

The selection of the counties of l’Anoia and Bages as recruitment areas is based on operational and organizational criteria, as the research team is embedded within the local primary care services, facilitating coordination and participant follow-up. L’Anoia represents a typical urban area in Catalonia (Igualada Urbà Primary Care Center), with demographic and health care characteristics comparable to similar regions, while the inclusion of the Bages region (Navàs Primary Care Center) provides representation of a rural setting. This dual approach ensures feasibility, consistency in intervention delivery, and participant retention, while also improving the external validity of the study by including both urban and rural populations.

One limitation of the study is that the intervention groups receive additional contact with physiotherapists and SMS reminders, while the control group only receives usual care. This greater interaction could introduce attention bias in patient-reported outcomes independently of the abdominal massage itself. Although a sham massage or a time-matched control condition would address this issue, we deliberately adopted a pragmatic design comparing the intervention with standard practice, as this better reflects real-world clinical conditions and enhances external validity.

Another limitation is the absence of a system to verify whether participants in the BIM group correctly perform the abdominal massages at home or whether they perform them at all. This lack of monitoring poses a threat to the internal validity of the study, as the actual exposure to the intervention may vary significantly between individuals. However, during the 2 in-person sessions, the physiotherapist will check that participants are performing the massages correctly. Future protocols should consider incorporating compliance tracking tools or remote follow-up to ensure adherence.

Additionally, the total sample size of 45 participants is relatively small for a 3-arm design with repeated follow-up, which may limit the generalizability of the findings. Moreover, recruitment is restricted to 2 geographic regions (Anoia, representing an urban area, and Bages, representing a rural area), which may affect the representativeness of the study population beyond these contexts.

Should the findings be favorable, future research should focus on scaling the intervention to other regions and health care systems, increasing the sample size, and assessing long-term outcomes, beyond 6 months. Moreover, future studies could include a sham massage group to control for attention bias and better isolate the effect of abdominal massage.