Objective: Large-scale disasters may disrupt health surveillance systems, depriving health officials and researchers of timely and accurate information needed to assess disaster-related health effects and leading to use of less reliable self-reports of health outcomes. In particular, ascertainment of cancer in a population is ordinarily obtained through linkage of self-reported data with regional cancer registries, but exclusive reliance on these sources following a disaster may result in lengthy delays or loss of critical data. To assess the impact of such reliance, we validated self-reported cancer in a cohort of 59,340 responders and survivors of the World Trade Center disaster against data from 11 state cancer registries (SCRs).
Methods: We focused on residents of the 11 states with SCRs and on cancers diagnosed from September 11, 2001, to the date of their last survey participation. Medical records were also sought in a subset of 595 self-reported cancer patients who were not recorded in an SCR.
Results: Overall sensitivity and specificity of self-reported cancer were 83.9% (95% confidence interval [CI] 81.9, 85.9) and 98.5% (95% CI 98.4, 98.6), respectively. Site-specific sensitivities were highest for pancreatic (90.9%) and testicular (82.4%) cancers and multiple myeloma (84.6%). Compared with enrollees with true-positive reports, enrollees with false-negative reports were more likely to be non-Hispanic black (adjusted odds ratio [aOR] = 1.8, 95% CI 1.2, 2.9) or Asian (aOR=2.2, 95% CI 1.2, 4.1). Among the 595 cases not recorded in an SCR, 13 of 62 (21%) cases confirmed through medical records were reportable to SCRs.
Conclusion: Self-report of cancer had relatively high sensitivity among adults exposed to the World Trade Center disaster, suggesting that self-reports of other disaster-related conditions less amenable to external validation may also be reasonably valid.