The effect of strengthening nurse practitioners’ competency in occupational health services for agricultural workers exposed to pesticides in primary care units, Thailand: a before-and-after study

Objectives

This study aimed to investigate the effectiveness of the SNPCOHS program in strengthening NPs’ competencies for providing occupational health services to agricultural workers exposed to pesticides in Thailand’s PCUs. The specific objectives were: (1) to assess changes in NPs’ professional attributes, knowledge, and skills in delivering occupational health services; and (2) to examine changes in NPs’ perceived self-efficacy in providing these services (Fig. 1).

Fig. 1.

Conceptual framework. SNPCOHS, Strengthening Nurse Practitioners’ Competency in Occupational Health Service; NP, nurse practitioner; PCU, primary care unit.

Ethics statement

This study was approved by the Ethical Review Committee for Human Research, Faculty of Public Health, Mahidol University (approval no., MUPH 2022-084). Written informed consent was obtained from all participants before data collection, and the study adhered to the principles of the Declaration of Helsinki.

Study design

This study employed a before and after design, specifically a non-equivalent comparison group pre- and post-test design, with time-based, non-randomized group assignment. A randomized controlled trial was not feasible due to several factors: (1) practical constraints in randomizing NPs in real-world PCU settings; (2) risk of contamination, as NPs may share knowledge and practices; (3) operational limitations in resource-constrained PCUs; (4) stakeholder and policy preferences for timely implementation; and (5) ethical concerns regarding withholding services from high-risk agricultural workers. The study was conducted in accordance with the TREND (Transparent Reporting of Evaluations with Nonrandomized Designs) statement and was registered with the Thai Clinical Trials Registry (TCTR20250115004).

Setting

Sixty NPs from PCUs in Chiang Rai Province were recruited, with 30 assigned to the comparison group and 30 to the experimental group. Enrollment occurred between August and December 2023. The comparison group completed questionnaires at 3 intervals, each separated by 4 weeks, using Google Forms (Google LLC). The experimental group completed the same questionnaires before the intervention, immediately post-intervention, and at follow-up.

Participants

A total of 60 NPs participated, all having at least 1 year of experience working in PCUs in Chiang Rai, Thailand. Participants were computer literate and had internet access. Initially, 64 NPs expressed interest and met inclusion criteria. Simple random sampling was used to select 60 NPs, evenly divided between experimental and comparison groups (Fig. 2). No participants withdrew during the study.

Fig. 2.

Flow diagram of participants for allocation.

Interventions

The SNPCOHS program, developed based on a literature review and grounded in the self-efficacy theory by Bandura [8], comprised 10 modules covering key topics such as pesticide fundamentals, occupational health laws, screening and referral, primary care, risk communication, and the role of nurses in occupational health services. A pilot test involved 5 NPs in Phayao Province.

The 4-week program (totaling 10 hours) integrated 4 self-efficacy strategies: enactive mastery, vicarious experience, verbal persuasion, and emotional arousal (Fig. 3). Activities included self-paced e-learning with video clips (Weeks 1–4), post-lesson quizzes (emotional arousal), case-based assignments (Weeks 2–3), and online discussions with peer-sharing and expert feedback (Week 4) (Supplement 1).

Fig. 3.

Example of activities applying 4 methods based on self-efficacy theory.

Outcome

The outcomes measured included 4 questionnaire subscales: professional attributes, knowledge, skills, and perceived self-efficacy in providing occupational health services at PCUs for agricultural workers exposed to pesticides (^{Dataset 1}).

Data sources/measurement

The instrument consisted of 3 parts: Part 1 included demographic variables: age, gender, marital status, highest educational level, length of work experience after completing an NP short course, and work in PCUs. Part 2 assessed professional attributes (10 items, 5-point Likert scale: 5=highest level of competency to 1=no competency), knowledge (18 true/false items), and skills (21 multiple-choice questions), based on the core competencies for Thai PCU nurses [10] and in-house occupational health service frameworks [5]. Part 3 measured perceived self-efficacy (16 items, 5-point Likert scale: 5=extremely confident to 1=not at all confident), grounded in self-efficacy theory [8] and aligned with the same competency frameworks. Content validity was assessed by 3 experts from occupational health services, toxicology, and occupational health nursing curriculum, yielding a content validity index of 0.97. Reliability was measured using KR-20 for knowledge (0.94) and Cronbach’s α for professional attributes (0.71), skills (0.72), and perceived self-efficacy (0.94).

Bias

Self-selection bias remains a concern due to voluntary participation. However, to minimize selection bias, the researchers tested the differences in baseline characteristics between the experimental and comparison groups, and found that the 2 groups were similar.

Study size

Sample size was calculated using G*Power ver. 3.1 (Heinrich-Heine-Universität Düsseldorf), with a power of 0.80, a significance level of 0.05, and an effect size of 0.933 derived from a prior study’s mean and standard deviation (comparison group: 73.66±13.70; experimental group: 83.12±4.20) [9]. The calculated required sample size was 40 NPs. To account for potential dropout, an additional 50% was recruited, resulting in 60 participants, evenly divided between groups.

Assignment method

The comparison group received basic patient care training from the Ministry of Public Health, identical to the training provided to the experimental group. After the study concluded, the comparison group received the SNPCOHS program.

Blinding (masking)

Blinding was not implemented due to the study’s voluntary nature and feasibility constraints. Data analysis was performed independently at the group level to reduce bias.

Unit of analysis

Data from all participants were analyzed by group.

Statistical methods

This study used IBM SPSS ver. 20.0 (IBM Corp.) for data analysis. Descriptive statistics (mean, standard deviation, frequency, percentage) were calculated to describe general participant characteristics. Group comparisons of age, work experience post-NP training, and PCU experience were performed using the Mann-Whitney U test due to non-normal distributions. Gender, marital status, and highest education were compared using the Fisher exact test, as more than 20% had expected counts less than 5.

The data on professional attributes, knowledge, skills, and perceived self-efficacy of both groups were normally distributed according to the Shapiro-Wilk test (P>0.05). The independent t-test was used to analyze differences in the mean scores between the experimental and comparison groups at each time point. Two-way repeated measures analysis of variance was conducted to examine the mean score of professional attributes, knowledge, skills, and perceived self-efficacy of NPs in providing in-house services across 3 time points: baseline, post-intervention, and follow-up. The assumption of sphericity was tested using the Mauchly test. Results indicated a violation of the sphericity assumption for professional attributes (P≥0.05). Consequently, the Greenhouse-Geisser correction was applied, as the epsilon (ε) value was ≤0.750.

Participants

The study included 60 NPs, with 30 participants in each group. Table 1 presents the demographic characteristics of each group. No statistically significant differences in baseline characteristics were observed between the groups (P>0.05).

Table 1.

Demographic characteristics of the experimental and comparison groups

Main results

The mean scores for NPs’ competency, including occupational health service professional attributes, knowledge, and skills, and their perceived self-efficacy in delivering in-house occupational health services showed significant differences between the experimental and comparison groups across different time points (P<0.05). Within-group comparisons over time also showed significant changes in both groups (P<0.05) (Table 2).

Table 2.

Differences in mean scores according to group, time, and between groups across different time points

In the experimental group, the mean scores for professional attributes, knowledge, skills, and perceived self-efficacy were significantly higher at post-intervention and follow-up than at baseline (P<0.05). However, no significant differences were observed between the scores at post-intervention and follow-up. In contrast, the comparison group showed no significant differences in any of the mean scores across time (Table 3).

Table 3.

Comparison of the mean differences in outcomes of the intervention group between baseline, week 4, and week 8

The analysis of baseline data using the independent t-test revealed no significant differences between the experimental and comparison groups for any of the variables (P≥0.05). However, at both post-intervention and follow-up, the experimental group demonstrated significantly higher mean scores across all variables than the comparison group (P<0.05) (Table 4).

Table 4.

Differences in outcomes between the experimental and comparison groups

Interpretation

The findings revealed meaningful improvements across 4 key domains—professional attributes, knowledge, skills, and perceived self-efficacy—among NPs providing in-house occupational health services. Specifically, participants demonstrated increased enthusiasm, leadership, and responsibility, indicating a positive shift in attitudes toward occupational health care. These improvements reflect a deeper recognition of nurses’ roles and a greater awareness of occupational risks among agricultural workers, particularly related to pesticide exposure.

In terms of knowledge, NPs gained substantial understanding of key occupational health concepts, such as pesticide safety, disease prevention, and integrating occupational health into routine nursing care. These advancements not only bolstered theoretical comprehension but also facilitated more accurate clinical documentation and informed decision-making, aligning clinical practices with academic and policy standards.

Skill development was evident in improved abilities for health promotion, inter-organizational collaboration, and effective communication regarding occupational risks. Nurses developed greater proficiency in coordinating with other sectors and conducting occupational health-related research, essential steps toward establishing comprehensive, community-based occupational health service models.

Perhaps most significantly, NPs reported increased confidence in delivering occupational health services. This increased self-efficacy suggests that training and practical experience empowered NPs to adopt more proactive roles, reinforcing the sustainable integration of occupational health services in primary care settings.

These changes are important because they directly support the expansion and effectiveness of occupational health services at the primary care level, in alignment with public health policies. They also reflect progress in building a workforce capable of addressing the complex needs of vulnerable working populations, ultimately contributing to the broader development of the occupational health system.

Comparison with previous relevant studies

This study observed immediate and sustained improvements in professional attributes, knowledge, skills, and self-efficacy among NPs participating in the SNPCOHS program delivered via online learning. Unlike prior research indicating that onsite training did not significantly improve professional attributes [11], these findings suggest online learning—providing flexibility and repeated access—may better facilitate professional growth. Similarly, blended learning approaches combining e-learning with interactive elements like case studies and peer discussions have been more effective than traditional methods in enhancing nurses’ knowledge and skills [12]. Additionally, the increased self-efficacy observed aligns with previous studies highlighting the positive impact of social support from supervisors and colleagues on practitioners’ confidence [13].

Limitations

The voluntary participation of NPs introduces the potential risk of self-selection bias, possibly affecting the generalizability of results. However, volunteers were not systematically different from non-volunteers regarding baseline occupational health knowledge, job responsibilities, or work locations. Additionally, current Ministry of Public Health policies in Thailand do not support occupational health training for primary care nurses, restricting such opportunities primarily to nurses in secondary or higher healthcare settings.

Generalizability

The study’s limited timeframe and inclusion of participants from a single province may limit its generalizability to NPs across the broader national context.

Suggestions

Outcomes (professional attributes, knowledge, skills) were not analyzed separately according to each of the 4 core competencies (interpersonal relationships, care management, integrated healthcare service, professional accountability). Future studies should assess outcomes separately for each competency to provide clearer evaluations.

Implications

The SNPCOHS program can be effectively integrated into educational curricula to enhance occupational health competencies among healthcare personnel, especially in Southeast Asian countries or regions heavily reliant on agriculture and extensive pesticide use. Providing targeted education to healthcare workers, particularly nurses, can significantly improve occupational health services for agricultural workers exposed to pesticides at PCUs.

Conclusion

The findings highlight the potential of the SNPCOHS program as a scalable model for enhancing occupational health competencies within PCUs. By equipping NPs with essential skills and confidence, the program addresses critical gaps in community-based occupational healthcare for underserved agricultural populations. The findings support investment in flexible, self-directed e-learning platforms as a strategy for strengthening public health workforces. Future research should explore sustainable and expansive interventions to facilitate long-term systemic improvements in occupational healthcare delivery.