CHAID analysis about using biological protection gloves as personal protective equipment (PPE) to protect occupational biohazards

2.1 Preparation of the questionnaire

A 34-question questionnaire, developed by the authors based on various sources of Spanish legislation regarding worker exposure to biological agents in occupational settings, emphasizes the key aspects that workers should consider protecting themselves from biological hazards [10].

The questionnaire uses a closed-ended format with single-choice, dichotomous answers (“yes” or “no”) to facilitate completion. In cases where a question is not relevant to the specific company or industry being evaluated, a third option of “not applicable” is provided.

An initial section was included in each questionnaire, consisting of eight items related to demographic data. These items covered sex, age, sector of activity of the company, and company size (categorized as micro, small-sized, or medium-sized companies). Additionally, we assessed the preventive system chosen by the company (whether they had an internal Health and Safety department or used external Health and Safety services) and the group classification of biological agents.

Utilizing hazard detection techniques and following the guidelines set up in Spanish regulations, we assessed response rates in the questionnaire using categories such as ‘very poor,’ ‘poor,’ ‘improvable,’ and ‘acceptable.’ Additionally, we evaluated workers’ exposure to occupational biological agents, considering levels such as ‘occasional,’ ‘irregular,’ ‘frequent,’ ‘very frequent,’ and ‘continuous.’ Questionnaire compliance is classified as ‘very poor’ when overall compliance is 25% or less, ‘poor’ when between 25% and 50%, ‘improvable’ when between 50% and 75%, and ‘acceptable’ when exceeding 75%. Worker exposure to biological agents depends on duration and frequency. Exposure is considered ‘casual’ if workers are exposed at least once a month (0.1–1% of working time), ‘irregular’ if exposed weekly (1–5% of working time), and ‘common’ if exposed more frequently.

Regarding the exposure of workers to biological agents in the workplace, it is essential to recognize that a threat or risk exists only when workers come into contact with these agents. Exposure is assessed based on the duration and frequency of such contact. In this context, casual exposure occurs when workers are exposed at least once a month or for 0.1–1% of their working time. Irregular exposure refers to situations where workers encounter biological agents at least once a week or between 1% and 5% of their working time. Common exposure happens when workers are exposed daily or for 5% to 10% of their working time. Quite common exposure occurs when workers face exposure at least once an hour or for 10% to 50% of their working time. Finally, exposure is considered continuous when it persists throughout the entire workday or exceeds 50% of working time.

2.2 Validation questionnaire

We conducted a descriptive analysis of the demographics of the companies taking part in the study. We analysed the frequency distribution (endorsement frequency) to find the proportion of unanswered items that were not understandable or interpretable. Fortunately, no item showed a low percentage of non-response, so removal was unnecessary.

Before conducting the factor analysis, we assessed the item-scale correlation by considering those items with a Pearson correlation coefficient greater than 0.30 [12].

For content validity, we employed the (CVR) proposed by Lawshe. Among the items, 11 obtained a CVR value of 0.8, while 23 of the remaining items achieved the maximum CVR value of 1.0. Consequently, no questions needed deletion from the questionnaires. Overall, the questionnaire showed a suitable level of content validity, with a mean CVR of 9.67 [12].

We employed principal components exploratory factor analysis, utilizing Varimax rotation to uncover the underlying factor structure. To validate the appropriateness of factor analysis, we assessed the Kaiser-Meyer-Olkin (KMO) measure and conducted Bartlett’s sphericity test. Items meeting specific criteria were considered: communalities greater than 0.5 and factor loadings greater than 0.25. Furthermore, we evaluated the internal consistency of items within each resulting factor using Cronbach’s Alpha coefficient ensuring that relevant Alpha values exceeded 0.70 [10]. Additionally, we assessed item stability through a test-retest trial, analysing correlations using Pearson’s test and calculating the weighted kappa coefficient with quadratic weights, along with their respective 95% confidence intervals. These rigorous assessments contribute to the robustness and reliability of our findings.

We conducted a segmentation analysis to facilitate the selection of variables in explaining responses to specific questions, with the dependent variable in focus. This statistical technique evaluates the dependence between variables, considering both the variable to be explained and other independent predictor variables. By grouping these variables effectively, we aim to generate the best possible associations [10].

In our study, we employed multivariate analysis using decision trees, specifically the Chi-square automatic interaction detector (CHAID) method [15]. We used three survey questions as dependent variables, capturing workers’ attitudes toward the use of personal protective equipment (PPE) for biological hazards. As independent variables, we considered sector activity, preventive systems, company size, age, gender of workers, overall compliance with the questionnaire, extent of worker exposure, and the group of biological agents to which workers are exposed.

All calculations were performed using the SPSS 21.0 statistical package for MAC.

CHAID analysis employs Automatic Interaction Detection using the χ² (chi-square) statistic. The outcome of this analysis is visually represented in a tree diagram, illustrating the successive segmentation process. At each node of the tree, the predictor variable that drives segmentation or shows the strongest interaction with the dependent variable is highlighted. Within each branch, the category defines a subgroup, along with its size. Additionally, each box displays the percentage distribution of the dependent variable within that subgroup [16].

The CHAID algorithm systematically selects the most significant predictor variables, prioritizing their order. By creating distinct population groups, it sheds light on the underlying causes of the dependent variable’s behaviour.

2.3 Inclusion/exclusion criteria

In our study, we investigated 51 Spanish companies where participants were included. These companies were selected based on their risk assessment, which showed potential exposure to biological risks for workers. We ensured that the companies were informed about the study’s purpose and the possibility of receiving relevant information.

A total of 518 participants (forming 193 women and 325 men) aged between 18 and 65 years were involved in the research. Data collection was carried out using a paper questionnaire, which was distributed by Occupational Risk Prevention Technicians from the participating companies. The questionnaire included informed consent details to ensure ethical participation.

3.1 Segmentation analysis

In the analysis of segmentation obtained, was considered the dependent variable to the question “Do you wear biological protection gloves (latex or equivalent) when handling potentially contaminated material? which has three categories: 86,5% yes, 11,0% no and 2,5% response is not appropriate.

About 8 variables considered in the study, four have been significant in this analysis: compliance with containment measures after analysis of workers, the size of the company, the time of exposure to biological agents and preventive system chosen by the company.

The compliance of questionnaire had greater significance. In this first division shows that the group of workers with a degree of compliance assessment in the questionnaire “improvable”, “poor” and “very poor” (Node 1), have a lower positive response (76,7%) in the use gloves than those with an acceptable degree of compliance (91,3%) (Node 2) having more workers with the latter group as they are 66.8% of the total.

From Node 1, two groups differ, the first (Node 3) about of workers who work in small-sized companies, in which moderate response rate affirmative use of gloves (73,4%), and the group formed is observed by workers in micro and medium-sized companies (Node 4), with a percentage of response to the question raised (82,5%), although with fewer workers in total (12,2%).

From Node 2 also differ two groups, the first (Node 5) formed by working with a degree of exposure to very frequent, frequent or irregular level to biological agents, in which a high percentage of positive response is observed to wear gloves (94,9%) and the group of workers with a degree of continuous exposure to biological agents (Node 6), with a percentage of response to the questions raised (78,1%).

Preventive system chosen by the company is the variable with the greatest discriminating power in the group of workers exposed to biological agents with very frequent, frequent or irregular level, obtaining the response to the use of gloves comes in a higher percentage (97,9%) for employees of undertakings with Internal Health and Safety Department (Node 8), the percentage (91,6%) of the employees of undertakings with External Health and Safety Service (Node 8).

Sorting the segments found it according to the degree of positive response on the variable “Using protective gloves,” an analysis with useful results are obtained to evaluate aspects related to the degree of use of PPE necessary for adequate protection against biological agents.

Table 4 shows that the first post is related to segment 4, where the groups of workers in enterprises with Internal Health and Safety department who are exposed to occupational biological agents very frequent, frequent or irregular shape and who have obtained a level of compliance questionnaire with acceptable result, with a glove use of 97,9%. The second shows that segment 3 is corresponding to the groups of workers in enterprises with External Health and Safety Service who are exposed to occupational biological agents very frequent, frequent or irregular shape and who have obtained a level of compliance questionnaire with acceptable result, with a use rate of 91,6%. In position 3, corresponding to segment 2, the groups of workers in medium-sized and micro-enterprises who have obtained a level of compliance questionnaire with “improvable”, “poor” or “very poor” result, with a use rate of 82 result 5%. The fourth, corresponding to segment 5, is the groups of workers exposed to occupational biological agents continuously and who have obtained a level of compliance questionnaire with acceptable result, with a percentage of 78,1%. In the last post Segment 1 corresponds to groups of workers in small-sized enterprises who have obtained a level of compliance questionnaire with “improvable”, “poor” or “very poor” result, where gloves use rate of 73,4% is observed.

This pioneering study in Spain evaluated the compliance with the mandatory use of gloves as personal protective equipment (PPE) against biological hazards. A survey was conducted among 519 employees from various Spanish firms where exposure to biological materials is common. It’s essential to acknowledge that corporate participation might introduce certain limitations, especially considering potential instances of non-adherence to Spanish regulations.

The insights gained from this research could be instrumental in advancing the safety and health of workers by highlighting key protective practices. Our research aimed at contributing to the diminishment of biological risk factors and bolstering the overall safety protocols through the examination of glove usage as PPE.