This cross-sectional study was conducted from March 2023 to November 2023. Convenience sampling was employed to select a study population of middle-aged and older hypertensive patients (aged 45 years or older) from 38 districts and counties in Chongqing Municipality (n = 558). Data was collected via a face-to-face questionnaire developed for this study.

Participants were included if they met the following criteria: aged 45 years or older; a prior diagnosis of hypertension at a township health center, community health service center, or equivalent facility at the monitoring site; and a mean systolic blood pressure ≥140 mmHg (1 mmHg = 0.133 kPa), a mean diastolic blood pressure ≥90 mmHg, or self-reported use of antihypertensive medication within the past 2 weeks. All participants were required to voluntarily consent to the survey. Individuals with mental disorders or significant difficulty communicating were excluded.

A self-administered questionnaire, based on the Theory of Planned Behavior (TPB) framework, was developed for this study. It comprised two parts: (a) essential demographic characteristics of the hypertensive patients (e.g., gender, ethnicity, place of residence, education level, and family history of hypertension) and (b) scales measuring TPB constructs. Scale development involved an extensive review of domestic and international literature on salt reduction intentions and behaviors. An initial item pool was established, refined through research team discussion and expert validation, and then pilot-tested. Data from 389 valid questionnaires in the pre-survey were analyzed using SPSS 27.0 and Amos 28.0 software. The entire scale showed excellent internal consistency (Cronbach’s alpha = 0.9000). Confirmatory Factor Analysis (CFA) indicated an acceptable model fit: χ²/df = 3.410, RMR = 0.056, RMSEA = 0.079, and GFI = 0.924 (12). Based on the statistical analysis results and expert judgement, the first draft was refined to form the final scale “Intention to Reduce Salt Diet Scale for Middle-aged and Older Hypertensive Patients in Chongqing Municipality Aged 45 Years and Above.”

The TPB scale consisted of four subscales with a total of 13 items: intention (3 items), perceived behavioral control over (3 items), subjective norms (3 items), and attitude (4 items). All items were rated on a Likert-type scale, with higher scores indicating stronger agreement with the statement.

During the survey design stage, the theoretical intention model was constructed, and subscales were designed for each of the model’s four core variables using the principles and methods of scale development. Reliability and validity tests were carried out, and any subscales with poor measurement performance were revised and improved. Before formally carrying out the cross-sectional surveys, the survey researchers underwent 1 day of unified and rigorous centralized professional training. Verification and proofreading were always conducted during the survey implementation stage and the data collation and analysis stage. Any mistakes, omissions, or logical errors found were revised promptly, and the questionnaire entries were double-checked. A total of 590 questionnaires were collected from middle-aged and older hypertensive patients. Of these, 12 refused to participate in the survey, and 20 questionnaires were excluded due to many missing values. The final number of valid questionnaires collected was 558.

The data were cleaned and analyzed using Stata 18.0 and Amos 28.0. Continuous variables are presented as the mean ± standard deviation, and categorical variables as the frequency (percentage). For descriptive purposes, participants were categorized into “high-intention” and “low-intention” groups based on the median score of the salt-reduction intention scale, to profile their distribution. Group differences in demographic characteristics were examined using an independent samples t-test or one-way ANOVA, with post-hoc tests applied where appropriate. Separate multiple linear regression models were developed for each of the four variables (attitudes, subjective norms, perceived behavioral control, and intentions) based on the results of the univariate analyses (p < 0.05), to identify demographic factors that were independent predictors of each construct. SEM was employed to test the hypothesized relationships based on the TPB. In the model, salt-reduction intention (as a continuous variable) was regressed onto three constructs: salt-reducing dietary attitudes, subjective norms, and perceived behavioral control. Bivariate correlations among these TPB constructs were also assessed. Model fit was evaluated using standard indices (e.g., χ²/df, CFI, TLI, and RMSEA). All statistical tests were two-tailed, and p < 0.05 was considered significant.

A total of 590 middle-aged and older patients with hypertension completed the questionnaire. Twelve patients refused to participate in the survey, resulting in a completion rate of 98%. Twenty questionnaires were excluded due to a high number of missing values, leaving 558 valid responses and a validity rate of 96.5%.

Among the participants, 55.2% were female, 48% had completed junior high school or higher, and 73.5% were married (Table 1). Nearly half (44.1%) were the primary food preparers in their households. A total of 50.5% reported no chronic comorbidities other than hypertension. The majority of the participants (61.3%) were older adults (≥65 years).

An independent sample t-test showed statistically significant differences in salt reduction dietary attitudes, subjective norms, perceived behavioral control, and intention scores between ethnic groups (p < 0.05). There were also statistically significant differences in perceived behavioral control scores for salt reduction between genders, with males scoring slightly lower than females in this domain (p < 0.05). One-way ANOVA revealed statistically significant differences across the urban–rural clusters in scores for all four TPB constructs: salt-reduction dietary attitude, perceived behavioral control, subjective norms, and intention (all p < 0.05). Additionally, statistically significant differences were observed in salt reduction dietary attitudes and intention among groups with different family histories of hypertension and occupational statuses (p < 0.05). When grouped by education level and marital status, differences in subjective norms scores for salt reduction were found (p < 0.05). Furthermore, statistically significant differences in perceived behavioral control scores for salt reduction and attitudes toward salt reduction were observed among those who were primary home cooks (p < 0.05, see Table 2).

Multiple linear regression analysis revealed that demographic characteristics, such as residence (urban–rural) and family history of hypertension, were the primary influencing factors of salt-reduction diet intention (p < 0.05). Gender and residence were associated with perceived behavioral control of salt reduction (p < 0.05). Residence, marital status, and educational attainment were correlated with subjective norms of salt reduction (p < 0.05). Furthermore, residence and family history of hypertension were related to the attitudes toward salt reduction (p < 0.05) (Table 3).

The final structural model is presented in Figure 2. Path coefficient tests for the effects of attitude, subjective norms, and perceived behavioral control on intention are detailed in Table 7. The analysis revealed significant direct effects of attitude and perceived behavioral control on intention. Specifically:

This indicates that a one-unit increase in the standardized score for attitudes is associated with a 0.22-unit increase in the intentions score, while a one-unit increase in perceived behavioral control is associated with a 0.70-unit increase in the intentions.

The present study found that, the intention to reduce salt intake was higher among middle-aged and older hypertensive patients aged 45 years or older in Chongqing (70.8%) than the proportion who were “not interested” in salt reduction in an international study involving seven countries (34%) (15), but significantly lower than in a survey based on the results of the China National Healthy Lifestyle Action WeChat Survey (90.2%) (16). This difference may be partly due to variations in the methodologies and target populations of the studies, and it highlights the significant potential for increasing the willingness of specific at-risk populations to reduce their salt intake. Complex cultural and cognitive mechanisms underlie differences in salt-reduction diets according to gender, family history of hypertension, and hometown. Etc. Specifically, men had lower perceived behavioral control over salt reduction than women, which may be related to women’s greater sense of control and self-efficacy over the amount of salt used when cooking for the family (17–19). Patients with a family history of hypertension had significantly higher mean salt reduction intention scores than those without, which may be attributed to their perceived risk of disease and stronger health beliefs (20). Additionally, salt reduction intentions were significantly higher among patients living in Central City, Chongqing Main City New Area, and Northeast Chongqing Three Gorges Reservoir, compared to those living in the towns in Southeast Chongqing Wuling Mountains Town Cluster. This reflects not only the differences in the availability of health resources but also the role of regional dietary culture and the socioeconomic environment on individual health beliefs and behavioral choices (21).

The present study confirms that a positive attitude toward a reduced-salt diet is an important factor in determining the intention of middle-aged and older hypertensive patients to reduce their salt intake. The WHO Global Report on sodium reduction highlights that reducing sodium intake is one of the most cost-effective ways to improve health and reduce the burden of non-communicable diseases, as it can prevent a significant number of cardiovascular events and deaths at a minimal total cost. The results of the present study show that more positive attitudes toward salt-reduction diets are associated with stronger intentions to follow such diets, which is consistent with previous studies (22, 23). Although salt reduction is often perceived by patients as a “negative” behavior that compromises tastes, the health benefits (e.g., blood pressure control) can be recognized and translated into positive behavioral intentions once acknowledged. Most consumers were willing to purchase salt-reduced foods even in the absence of a salt-reduction goal, suggesting that they perceived positive health outcomes from salt reduction (24). Residents with high levels of salt-reduction dietary attitudes were more likely to take the initiative to reduce salt intake (25, 26). Individuals’ evaluations of whether they approve or disapprove of a certain behavior influence their attitudes toward it, which ultimately affect its implementation (27). For example, they could be given targeted salt-reduction education to help them understand the main source of sodium in their diet (about 76% of salt intake in China comes from home cooking) (28). This would enable them to develop a correct understanding of a salt-reduction diet, fully grasp the harm caused by a high-salt diet, and change their negative attitudes toward it. If they already have a positive attitude toward a low-salt diet, the sodium-reduction education could further strengthen this.

Unexpectedly, the subjective norms of a salt-reduced diet were not found to be significantly and directly associated with the intention to reduce salt intake in the present study. This is consistent with the findings of Alshagrawi et al. (29) in the field of vaccination, which suggest the existence of boundary conditions for the effect of social pressure. The unique communal eating culture and highly consistent “heavy” food preferences in Chongqing make it more difficult to obtain differentiated low-salt dietary advice or support from significant others (e.g., family and friends) (30, 31), which may diminish the predictive power of subjective norms. Furthermore, one study suggests that family disapproval acts as a deterrent to reducing salt intake (32, 33). However, this does not dismiss the role of social influence. A national research study found that exhortations from physicians and reminders from family members helped residents to begin reducing their salt intake (34). Therefore, future interventions may consider innovative strategies, such as integrating salt reduction advocacy into family or community group activities and establishing effective, positive social norms based on the local culture and environment.

The most critical finding of this study is that, in the theoretical model, perceived behavioral control is the strongest predictor of salt reduction dietary intentions in older hypertensive patients, with predictive power that exceeds that of attitudes. This aligns with the TPB expectation that, when behaviors are perceived as difficult to perform, an individual’s confidence in their own ability becomes the dominant factor in decision-making. Chongqing is one of the‘heavy’food cities and has a strong culture of gathering and eating. For middle-aged and older patients with hypertension, reducing salt intake involves overcoming multiple barriers, such as long-term taste dependence (35, 36) and the practical difficulties of obtaining low-sodium alternatives (37), as well as coping with “invisible salt” in pre-processed foods and when eating out (38). Therefore, high levels of PBC imply that patients believe they can overcome these challenges and are more likely to develop a firm intention to reduce their salt intake.

This finding has a central implication for interventions, namely that the most effective ones need to go beyond disseminating knowledge alone, which will not solve the real problem of a “sense of control.” Future interventions must systematically lower the behavioral threshold. Examples include promoting affordable low-sodium salt, encouraging restaurants to offer low-salt options, and teaching food label reading and low-salt cooking skills through community education programs. A targeted health communication campaign that taught these skills successfully encouraged 85% of respondents to report positive changes in their attitudes and behaviors, and 90% of participants developed a clear intention to reduce their salt intake (39). This strongly supports the feasibility of bridging the “intention-behavior gap” by enhancing PBC, given the strong association between behavioral control and desire-intention. Therefore, a multi-level empowerment system integrating policy support, environmental modification, and skill training for middle-aged and older hypertensive patients in Chongqing may be useful to transform salt reduction intentions into actual actions.

This cross-sectional study surveyed the dietary intention of salt reduction among hypertensive patients aged 45 and over in Chongqing City. The study used a self-constructed scale and had the following limitations. First, the cross-sectional design did not allow time-series relationships among the variables to be identified, making it difficult to infer causality. Secondly, although SEM analyses were able to test the hypothesized paths, the results were highly dependent on the quality of the measurements and the model setup and did not confirm causality; notably, the RMSEA value (0.083) was slightly above the ideal threshold, which may relate to sample size or model complexity, though other key indices (e.g., CFI, TLI) were acceptable and the core findings remain valid. Thirdly, the survey instrument was primarily based on the theoretical framework of planned behavior and existing literature. Qualitative interviews were not conducted in the prior period, nor was the Delphi expert consultation method refined, which may affect the scale’s measurement accuracy. Fourthly, potential selection bias due to convenience sampling, the data were derived from participants’ self-reports, which may have introduced information bias. Finally, due to geographical and condition-related limitations, the researchers were unable to conduct follow-up visits to assess patients’ actual behavioral changes after they had expressed their intention to reduce salt intake. Therefore, we recommend that future studies conduct reinterviews and expert consultations during the instrument development phase and use longitudinal designs wherever possible to track the dynamic relationship between intention and behavior.