Author s response to reviews Title: Effectiveness of an educational intervention for sodium restriction in patients with hypertension: study protocol for a randomized controlled trial Authors: Marcela Rodrigues (perdomomr@gmail.com) Luciana Santos (lksantos@hcpa.edu.br) Flávio Fuchs (ffuchs@hcpa.edu.br) Sandra Fuchs (sfuchs@hcpa.edu.br) Leila Moreira (lbmoreira@hcpa.edu.br) Version: 1 Date: 11 May 2017 Author s response to reviews: TRLS-D-16-00717 The effectiveness of an educational intervention for sodium restriction in patients with hypertension: study protocol for a randomized controlled trial Marcela Perdomo Rodrigues, RDN; MsC; Luciana kaercher John dos Santos, RDN; Flávio Danni Fuchs, MD PhD; Sandra Costa Fuchs, MD PhD; Leila Beltrami Moreira, MD PhD Trials Dear Editor Thank you for the careful revision of our manuscript. We revised point-by-point and we hope we have fully answered all comments. Best regards,
Editorial Office comments: - Please change the heading 'Introduction' to 'Background' in both the abstract and main manuscript file. Response: Replaced by Background in the main manuscript - As your trial was retrospectively registered, please clearly state this following the trial registration number and date of registration. Response: included Trial registration number: ClinicalTrials.gov Identifier NCT02848690 ( retrospectively registered: 27 July 2016) - Trials requires the submission of a populated SPIRIT checklist and figure for all study protocols. Response: The figure was included as an attached figure file and the checklist is provided as an additional file Both the figure and the checklist are referenced in the main manuscript text. - Please remove the ethical approval and funding documents from the additional files, we cannot publish these. Response: The documents were removed. Reviewer Comments Major suggestions: 1. In introduction (lines 84 to 87), authors stated, "The effectiveness of non-pharmacological interventions in blood pressure reduction, as sodium intake restriction has been evidenced by several studies". To support, they used references published before 2014 and 2015. However, since 2014-2015 some publications are not agree with this affirmation, including a Cochrane review. Therefore, I believe that authors would review and include this topic in the introduction. At a minimum, the current controversy should be presented and allowed to the reader knows this situation. Some elements that are needing consider could be: * A 2014 Cochrane review evaluating dietary sodium restriction in normotensive and hypertensive patients showed no effect on cardiovascular outcomes or all-cause mortality.
Therefore, authors concluded that prospective evidence currently does not support sodium restriction. (Adler AJ, et al. Reduced dietary salt for the prevention of cardiovascular disease. Cochrane Data base Syst Rev. 2014;(12):CD009217) * Current evidence suggests a J-shaped association between sodium intake and cardiovascular disease: the lowest risk is associated with consumption of 3 to 5 g of sodium per day. (O'Donnell M, Mente A, Yusuf S. Sodium intake and cardiovascular health. Circ Res. 2015;116(6):1046-1057.). Similarly, Mente A, et al., provide reasonable evidence that current dietary levels of salt in most populations are associated with the lowest incidence of cardiovascular events. However, these authors so concluded that there are association of low sodium intake (below 3 g/day) with increased risk of cardiovascular events and death in both hypertensive and normotensive persons. (Mente A, et al. Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies. Lancet 2016; 388: 465-75). Obviously, according to work, authors would prove information that support the effect of high intake of sodium on hypertension, therefore, it is important for physicians to recommend dietary patterns that are moderate in sodium. We used consisted evidence based on the Dietary Approaches to Stop Hypertension (DASH). The text was modified as follows: Clinic trials have demonstrated the efficacy of nutritional interventions in the reduction of blood pressure1-6. According to a meta-analysis, the sodium intake restriction has shown effectiveness in reducing blood pressure in hypertension and normotension individuals7. Even salt-restriction diets, as DASH (Dietary approaches to Stop Hypertension) 1-2 and Mediterranean diet6 were associated with the decrease of the blood pressure levels. The guidelines to reduce salt intake to 5-6 g/day will have a major effect on blood pressure, but a further reduction to 3 g/day will have a greater effect and should become the long-term target for population salt intake (He FJ, MacGregor GA. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database Syst Rev 2004:CD004937). In contrast, evidence have been demonstrated in hypertension and normotension individuals, there is an increased risk of cardiovascular disease events and deaths associated with 24-h urinary sodium excretion of less than 3 g/day. However, high sodium intake (greater than 6 g/day) was associated with an increased risk in individuals with hypertension. These data suggest that lowering sodium intake is best targeted at populations with hypertension who consume high sodium diets (Mente A, et al. Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies. Lancet 2016; 388: 465-75). Thus, current evidence suggests a recommendation for moderate
sodium intake in the general population (3 5 g/d), with targeting the lower end of the moderate range among those with hypertension (O'Donnell M, Mente A, Yusuf S. Sodium intake and cardiovascular health. Circ Res. 2015;116(6):1046-1057.). 2. Objective (in both abstract and text) needs more detail. Reader should understand how will be assess the effectiveness of the education intervention (how it will be measure?). Similarly, it is important to detail which the comparator is (usual care?). The text was modified as follows: This study aims to describe the protocol and randomization of the clinical trial design in order to evaluate the effectiveness of an education intervention based on DSRQ scores. The effectiveness measures are the DSRQ score variation and the urinary sodium values reduction from baseline and after two and six months. 3. Hypothesis (lines 126-128). Please, consider to adjust according to variables of primary outcomes (changes from baseline, after 8 weeks and 6 months in DSRQ score, urinary sodium values and blood pressure mean assessed by ABPM). The text was modified as follows: Patients with hypertension who participate in the intervention group show low-sodium diet adherence, which decreases blood pressure values assessed by ABPM and sodium urine excretion values after two and six months in comparison to the control group. 4. Study variables and methods of assessment (lines 190-218). Please consider to prove more details regarding to date collection (e.g. who will collected or assessed) and data management. The researches team will be responsible for triage and selection of eligible participants, and three members of the team will obtain the signatures of the written informed consent prior to entering the study. Researchers will not be blinded to participant s intervention. The investigators will be trained to perform anthropometric standardization and blood pressure measurements as well as the application of questionnaires. A laboratory technician will collect both spot urine and blood collection after 12 hours fasting and the samples will be forwarded for analysis.
5. Before sample size. Please consider include some information regarding subject withdrawal or termination. We opted for a 20% increase over the initial number to account for follow-up loss or subject withdrawal so that we arrived at a total of 120 participants included and assigned to either intervention or control group. 6. Sample size (line 226). I believe that authors would explain why the sample size is not estimated according to some primary outcomes data: changes from baseline, after 6 months in DSRQ score, urinary sodium values, or blood pressure mean. We estimated the sample size according to sodium reduction because the DSRQ was developed in order to improve sodium restriction adherence, understanding that a greater restriction decreases sodium intake, which, in turn, reduces urinary sodium values and blood pressure mean after two and six months. 7. Control group. Please prove more details relate to: "During six months, they will be monitored monthly for evaluation in usual care". What it is mean? It means that the participants of the control group will have blood pressure, body weight and waist circumference measures assessed monthly. The text was modified as follows: During six months, participants of the control group will have blood pressure, body weight and waist circumference measures assessed monthly. During the same period of time, participants will be also asked if they have any questions about food. 8. Educational intervention group (intervention group). Please include more details about the personal/professionals who participate in the educational intervention group and their training. For instance, who and what kind of training has person who apply the DSRQ? Who and what kind of training has person who make the intervention based on the result of the food record (attitude), etc. This information could be include in table 1. It is very important to discuss the implantation and use of the future results. Results are attribute to one specific professional or to a health care team? The intervention sessions are designed according to the subscales of DSRQ, and they will all be developed and performed by the nutritionist, who is the investigator responsible for the educational intervention, based on the Planned Behavioral Theory (Ajzen).
9. Discussion (line 256). Authors stated that DSRQ was validated for Hypertension and prove as support reference 26 (Rodrigues MP. Avaliação da associação de consumo de feijão com arroz e pressão arterial em indivíduos hipertensos em tratamento. Master's thesis UFRGS - Universidade Federal do Rio grande do Sul; 2014. http://www.lume.ufrgs.br/handle/10183/127383.) I believe that this link is incorrect. Reference is linked to to Incidência de hipertensão arterial em uma coorte de adultos da região urbana de Porto Alegre/RS. Therefore, there is concern regarding if the instrument is validated or not. So, please prove a correct reference that support this topic. This link was wrong, the correct reference is: Rodrigues MP. Avaliação da associação de consumo de feijão com arroz e pressão arterial em indivíduos hipertensos em tratamento. Master's thesis UFRGS - Universidade Federal do Rio grande do Sul; 2014 https://www.lume.ufrgs.br/handle/10183/127384 10. Before trial status, please consider to include some information regarding some potential biases that could affect the results This study has some limitations. It is difficult to target a specific behavior concerning salt intake because it can be originated from several natural sources or be added in food during cooking or food processing. The instrument is self-reported, and self-reported behavior measurement can present a range of bias, such as the data credibility. The open label design can introduce some potential for biases and the sample size limits the external validity. 11. Figure 1. Please consider to change the title by: General overview of study design. Most important, I believe that this figure would prove more details of the respectively step. For instance in access eligibility, who randomized? What is accessed in 8 week 8, and 6 month). Please consider to use months as variable for period of time (2 and 6 months). Suggestion accepted. Minor suggestions: 1. Title. Please consider to change by: effectiveness of an educational intervention for sodium restriction in patients with hypertension: study protocol for a randomized controlled trial. Suggestion accepted.
2. Introduction: It is important to include some information regarding to Dietary Sodium Restriction Questionnaire (DSRQ). At minimum support that it is an instrument useful to improve adherence to a lifestyle modification program. The Dietary Sodium Restriction Questionnaire (DSRQ) was developed due to the lack of instruments for measuring low sodium diet among patients with heart failure (HF), in order to improve the adherence to a low sodium diet 17. This questionnaire aims to help identify facilitators and barriers to the adherence to a low sodium diet, which is useful in clinical practice in order to guide the development of interventions for the education and counseling of the patients17. 3. Introduction: Lines 87 to 90, please consider reviewing the sentence, it is longer and imprecise. We revised this sentence. See the item Major suggestions: 1. 4. Study Design (line 131). Please consider include that it is a single center. We agreed to include single center. 5. In education intervention group (lines 170-171). Please prove reference for the instrument "Educational intervention about sodium restriction will be based on the results of the DSRQ (reference) application" The educational intervention on sodium restriction will be based on the results of the DSRQ, validated for hypertension. The instruments applied are described in Rodrigues MP, Rabelo- Silva E, Fuchs FD, Fuchs SC, Moreira LB. Validity and reliability of the dietary sodium restriction questionnaire in patients with hypertension. Eur J Clin Nutr.. 2017 Apr;71(4):552-554. The educational intervention will be based on the article Welsh D, Lennie TA, Marcinek R, Biddle MJ, Abshire D, Bentley B, Moser D. Low-sodium diet self-management intervention in heart failure: pilot study results. Eur J of Cardiov nursing 2012; 12(1)87-95 and Welsh D, Marcinek R, Abshire D, Lennie T, Biddle M, Bentley B, Moser D. Theory-based Low-Sodium Diet Education for Heart Failure Patients. Home Healthc Nurse. 2010 ; 28(7): 432 443.
7. Statistical Analysis Plan. Last sentence (line 243), please consider change by: All data will be analyzed according to the intention-to-treat principle. Change accepted. 8. Ethical Approval and consent to participate (line 297). Please consider to include and health care. Change accepted: It is essential for participants to know that they can withdraw the study at any time and their participation will not interfere in their usual treatment and health care. 9. References. Please review and adjusted according to reference style, mainly authors that should be included in reference lists For instance, references number 1, 2, 3 So, some grammar mistakes and journal abbreviations, for instance reference 7 The American Journal of Preventive Medicine2005 (iso abbreviation is Am J Prev Med). We revised and corrected according to reference style.