Using the Symptoms and Perceptions (SaP) Questionnaire for Disaster and Environmental Health Research: Analysis Across Multiple Exposure Contexts

Introduction: The Symptoms and Perceptions (SaP) questionnaire is a tool developed to assess the occurrence, duration, and severity of physical and psychological symptoms in epidemiological research. The questionnaire covers up to thirty symptoms across multiple organ systems, alongside perceptions and causal beliefs. This study assesses the reliability and validity of the SaP using data from five independent population studies, representing different sample groups, exposure contexts, and timeframes. The main objective is to better understand the potential for standardized symptom assessment in disaster and environmental health studies. Methods: Data from five epidemiological studies in the Netherlands were combined and analyzed. Each health study employed the SaP questionnaire with minor variations in item structure and content (28 to 30 symptom items): Study 1. Electromagnetic fields (N = 5,933; 2011); Study 2. Pesticides (N = 3,756; 2017); Study 3. Industrial area with multiple incidents (N = 2,394; 2020); Study 4. COVID-19 pandemic in a large province (N = 45,903; 2020); Study 5. National health monitor (N = 315,586; 2022). Various indicators of consistency and validity were assessed. Confirmatory factor analysis was performed to evaluate construct validity and dimensionality. In the analyses, a broad range of additional variables was included, such as psychological measures, health data registered in primary care, and proxies of actual and perceived exposure. Results: Analyses showed good internal consistency (Cronbach’s alpha > 0.80 across studies) and convergent and divergent validity, based on associations between symptom scores and data from diverse constructs. Higher levels of perceived exposure were typically accompanied by higher levels of symptom report. The factorial structure of the symptom assessment was confirmed, yielding consistent clusters of symptoms across datasets, in line with primary care classifications. Conclusion: While existing literature predominantly focuses on psychological problems or disorders, a comprehensive and standardized symptom assessment approach is of importance, regardless of the nature and timeframe of an exposure case.