Source Paper
Mark Farfel, Laura DiGrande, Robert Brackbill, Angela Prann, James Cone et al.
Journal of Urban Health • 2008
To date, health effects of exposure to the September 11, 2001 disaster in New York City have been studied in specific groups, but no studies have estimated its impact across the different exposed populations. This report provides an overview of the World Trade Center Health Registry (WTCHR) enrollees, their exposures, and their respiratory and mental health outcomes 2-3 years post-9/11. Results are extrapolated to the estimated universe of people eligible to enroll in the WTCHR to determine magnitude of impact. Building occupants, persons on the street or in transit in lower Manhattan on 9/11, local residents, rescue and recovery workers/volunteers, and area school children and staff were interviewed and enrolled in the WTCHR between September 2003 and November 2004. A total of 71,437 people enrolled in the WTCHR, for 17.4% coverage of the estimated eligible exposed population (nearly 410,000); 30% were recruited from lists, and 70% were self-identified. Many reported being in the dust cloud from the collapsing WTC Towers (51%), witnessing traumatic events (70%), or sustaining an injury (13%). After 9/11, 67% of adult enrollees reported new or worsening respiratory symptoms, 3% reported newly diagnosed asthma, 16% screened positive for probable posttraumatic stress disorder (PTSD), and 8% for serious psychological distress (SPD). Newly diagnosed asthma was most common among rescue and recovery workers who worked on the debris pile (4.1%). PTSD was higher among those who reported Hispanic ethnicity (30%), household income < $25,000 (31%), or being injured (35%). Using previously published estimates of the total number of exposed people per WTCHR eligibility criteria, we estimate between 3,800 and 12,600 adults experienced newly diagnosed asthma and 34,600-70,200 adults experienced PTSD following the attacks, suggesting extensive adverse health impacts beyond the immediate deaths and injuries from the acute event.
Objective: To assess exposure, physical health outcomes, and mental health outcomes among individuals exposed to the 9/11 World Trade Center attacks through baseline survey interviews
Gather these items before starting the experiment. Check off items as you prepare.
SAS Institute • N/A
Chow and Rodgers • N/A
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Registrants were recruited through outreach to eligible individuals and groups, local and regional media, and lists provided by employers and governmental agencies. Individuals were also contacted through widespread advertising campaign encouraging enrollment via toll-free number or WTCHR website preregistration
Note: 232 lists representing 135,450 potential registrants were provided. Key resource was Port Authority list with 95,442 names of WTC building security clearance holders
“Registrants were recruited for enrollment through outreach to eligible individuals and groups, as well as local and regional media. Lists of names and associated contact information of potentially eligible persons were provided voluntarily by entities such as employers and governmental agencies”
Obtain informed consent from all participants prior to interview
Note: WTCHR protocol approved by Institutional Review Boards of CDC and NYC DOHMH in 2003. Federal Certificate of Confidentiality obtained
“The interview included: (a) informed consent”
Verify participant meets one of four eligibility criteria: (1) present south of Chambers Street on 9/11; (2) rescue/recovery worker or volunteer at WTC site September 11, 2001 through June 30, 2002; (3) primary residence south of Canal Street on 9/11; (4) student or staff at schools south of Canal Street on 9/11
Note: Estimated total eligible population was 409,492 individuals
“determination of eligibility; (c) demographics”
Record participant demographics and contact information for follow-up, including information on up to three people likely to know future whereabouts
Note: N/A
“demographics; (d) contact information for follow-up (including information on up to three people who would be likely to know the future whereabouts of the respondent)”
Ask general exposure questions including being caught in dust and debris cloud, time and location in dust cloud, witnessing potentially traumatizing events (airplane hit, building collapse, people running, injured/killed persons, people falling/jumping), and types of injuries sustained on 9/11
Note: N/A
“general exposure questions (e.g., to the dust and debris cloud); (f) specific exposure assessment sections for each of the four eligibility groups”
Administer specific exposure questions tailored to each eligibility group. Residents asked about evacuation and home return date. Building occupants asked about workplace return date. Rescue/recovery workers asked about work sites, dates worked, and activity types
Note: Time periods for post-9/11 exposure analysis based on meteorological data including rainfall dates (September 14, 19, 2001) and fire extinguishment date (December 19, 2001)
“Residents, for example, were asked questions about evacuation from their home, including the date of return to their home. Building occupants who evacuated a building on 9/11 were asked about the date of return to their workplace. Rescue/recovery workers and volunteers were asked questions about their work site(s), including dates worked and types of activities”
Ask about injuries sustained on 9/11 ranging from eye injury or irritation to fractures, burns, and concussions
Note: N/A
“9/11 injuries; (h) physical health symptoms and conditions before and after 9/11”
Ask about new or worsening respiratory symptoms at any time after 9/11, new or worsening nonrespiratory symptoms (hearing problems, severe headaches, heartburn, indigestion, reflux, skin rash/irritation), and specific conditions diagnosed by physician anytime in 2-3 years after 9/11 (asthma, emphysema, hypertension, coronary heart disease, angina, heart attack, diabetes, stroke, cancer/malignancy)
Note: Questions similar to well-tested examples from Behavioral Risk Factor Surveillance System
“Enrollees were asked about physical health outcomes, including: (a) injuries sustained on 9/11 ranging from eye injury or irritation to fractures, burns and concussions; (b) new or worsening respiratory symptoms at any time after 9/11”
Administer Kessler-6 scale (K-6) to assess serious psychological distress in 30 days prior to interview. Score above cutoff of 13 indicates current SPD
Note: K-6 is correlated with diagnostic measures of major depressive disorder, generalized anxiety disorder, schizophrenia, and other mental disorders
“The Kessler-6 scale (K-6), used to determine SPD, is a psychometrically validated, epidemiologic screening measure used in the National Health Interview Survey since 1997”
Administer PTSD-Checklist Civilian Version (PCL), a 17-item symptom scale corresponding to DSM-IV criteria. Sum item responses and use cutoff of 44 to classify individuals as likely PTSD cases
Note: PCL first validated with U.S. veterans, later validated for civilian populations exposed to assault, motor vehicle trauma, and life-threatening illnesses
“The adult interview also included the PTSD-Checklist Civilian Version (PCL), a 17-item symptom scale corresponding to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, DSM-IV criteria”
For children under 18 years at time of interview, parents and guardians serve as proxies and complete eight-question scale derived from Hoven et al. to assess possible posttraumatic stress symptoms
Note: Total of 3,100 proxy interviews completed: 2,635 for children under 18, 157 for deceased adults, 308 for seriously disabled or unable to respond adults
“Proxy interviews with parents and guardians of child enrollees included an eight-question scale derived from Hoven et al. to assess possible posttraumatic stress symptoms”
Interviewer takes actions if respondent's answers or behavior indicate emotional distress, including suggesting breaks, stopping interview, or providing referrals
Note: N/A
“The interviewer took actions (e.g., suggested taking a break, stopped the interview, provided a referral) if a respondent's answers or behavior indicated emotional distress”
Administer questionnaire in English (95.2%), Spanish (1.9%), Cantonese (1.5%), and Mandarin (1.0%). Use translation service vendor for registrants whose primary language was not pretranslated (n=315)
Note: Baseline interviews conducted between September 2003 and November 2004 (2-3 years post-9/11)
“The questionnaire was administered in four languages: English (95.2%), Spanish (1.9%), Cantonese (1.5%), and Mandarin (1.0%)”
Complete 67,527 interviews (95%) using computer-assisted telephone interviewing (CATI) and 3,910 interviews (5%) using computer-assisted in-person personal interviewing (CAPI)
Note: Total of 71,437 baseline interviews conducted between September 2003 and November 2004
“Of the 71,437 baseline interviews conducted between September 2003 and November 2004 (2–3 years post-9/11), 67,527 (95%) were completed using computer-assisted telephone interviewing (CATI) and the remaining 3,910 were completed using computer-assisted in-person personal interviewing (CAPI)”
For enrollees reporting being caught in dust cloud, record geographic location using street address (n=15,167), closest cross street intersection (n=11,329), closest landmark (n=10,732), or closest subway stop (n=1,119). Use DCP Geosupport application for automated batch matching of street addresses and LION geodatabase for geocoding intersections and manual address matching
Note: Geocoding occurred only if enrollee answered yes to being caught in dust cloud
“Enrollees were asked about their geographic location when they first encountered the dust cloud. Locator variables included street address ( n =15,167), closest cross street intersection (n=11,329), closest landmark ( n =10,732), and the closest subway stop ( n =1,119)”
Create standard deviational ellipse centered on mean center of all geocodable dust cloud encounter locations, with long axis in direction of maximum dispersion and short axis in direction of minimum dispersion. 1 and 2 standard deviational ellipses correspond to 68.2% and 95.4% of geocoded data respectively
Note: N/A
“A standard deviational ellipse was constructed, centered on the mean center of all the geocodable locations reported by enrollees when they first encountered the dust cloud, with its long axis in the direction of maximum dispersion and its short axis in the direction of minimum dispersion”
Use SAS version 9.1 to compute descriptive statistics and bivariate associations between health symptoms/conditions and demographic characteristics, risk factors, and selected event exposures. Use Chi-square and Cochran-Armitage tests to determine statistical significance
Note: All enrollees included in data analysis. Analyses of respiratory and mental health outcomes restricted to adult enrollees (>18 years) at time of interview, including 157 decedents
“SAS ® (version 9.1) was used to compute descriptive statistics and bivariate associations between health symptoms or conditions and demographic characteristics, risk factors, and selected event exposures and experiences”
Use Chow and Rodgers' Euler-Venn applet software to create proportional-to-size Venn diagram depicting overlap in eligibility criteria among enrollees
Note: N/A
“Chow and Rodgers' Euler–Venn applet software was used to create a proportional-to-size Venn diagram to depict overlap in eligibility criteria among enrollees”
Apply prevalence of self-reported health problems among enrollees to estimates of total exposed population for each eligibility category. Calculate three estimates: (1) midpoint estimate assuming ill persons more likely to self-enroll; (2) upper bound assuming self-identified prevalence representative of entire population; (3) lower bound assuming symptomatic list-identified persons 50% more likely to enroll than asymptomatic. Round estimates to nearest hundred
Note: Prevalence of self-reported disease higher among self-identified than list-identified persons for all exposed categories and health problems
“To construct a plausible midpoint estimate of total number of ill adults, we assumed that ill persons were more likely to self-enroll in the WTCHR. The midpoint estimate of persons made ill was therefore calculated as the percentage of those with health problems among list-identified persons multiplied by the total population exposed”
Four eligibility groups: (1) people present south of Chambers Street in lower Manhattan on 9/11; (2) rescue/recovery workers and volunteers at WTC site September 11, 2001 through June 30, 2002; (3) people with primary residence south of Canal Street on 9/11; (4) students and staff at schools south of Canal Street on 9/11