Environmental Context and Reporting Completeness of Event-Based Ecological Momentary Assessment in Cigarette and Cannabis Use.

Han J.; Desjardins M.; McQuoid J.; Devkota J.; Waring J.; Lopez-Paguyo K.; Nguyen N.; Ling P.; Thrul J. · Drug and alcohol review · 2026

**Background & Methods** This study examined how environmental context affects the completeness of event-based ecological momentary assessment (EMA) reporting of cigarette and cannabis use in young adults. Researchers analyzed 30 days of GPS-enabled EMA and daily diary data from 34 participants in California (730 participant days), using the Social Vulnerability Index to classify the socioeconomic characteristics of participants' daily activity spaces. **Key Findings** • Higher social vulnerability in daily activity spaces relative to home was significantly associated with underreporting of substance use through EMA: cigarettes (adjusted odds ratio [aOR] 1.55, 95% credible interval [CrI] 1.25-1.93) and cannabis (aOR 1.28, 95% CrI 1.06-1.55). • Participants were less likely to report their actual use events in real-time when visiting socially vulnerable neighborhoods compared to their home environment, suggesting that contextual factors influence reporting completeness. • The underreporting pattern for cigarettes was replicated in a larger independent dataset, strengthening the reliability of findings across populations. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. **Evidence Quality** This study presents preliminary evidence with notable limitations. The primary analysis uses a small sample size (n=34), which restricts generalizability despite Bayesian methodology providing probabilistic estimates rather than traditional confidence intervals. The reliance on daily diary recall as the comparison metric introduces potential bias, as diaries themselves may be subject to recall error or incomplete reporting. The cross-sectional nature of the analysis prevents causal inference about whether environmental stress directly impairs real-time reporting or if other unmeasured confounders mediate this relationship. Strengths include objective GPS data for environmental classification and validation in an independent larger dataset for cigarette outcomes. The study provides important methodological insights for substance use research rather than clinical evidence. Researchers should interpret findings as supporting the need for environmental context consideration in EMA study design and data interpretation rather than establishing definitive relationships between social vulnerability and reporting behavior.

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