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: Assessment of post-9/11 respiratory symptoms and newly diagnosed asthma among enrollees with no prior asthma history, as part of the World Trade Center Health Registry
Gather these items before starting the experiment. Check off items as you prepare.
SAS Institute • N/A
Chow and Rodgers • N/A
As an Amazon Associate, we earn from qualifying purchases. Product links help support this free resource.
The World Trade Center Health Registry (WTCHR) was created in July 2002 as a collaborative effort between ATSDR and NYC DOHMH. Eligibility criteria were developed accounting for proximity by time and place to WTC attack, acute exposure to dust/debris cloud, and chronic exposure to smoke/fumes.
Note: Four broad eligibility groups were constructed based on location and exposure characteristics
“The WTCHR was created in July 2002 as a collaborative effort between the Agency for Toxic Substances and Disease Registry (ATSDR) and the New York City Department of Health and Mental Hygiene (NYC DOHMH)”
Registrants were recruited through outreach to eligible individuals and groups, local and regional media, and lists provided by employers and governmental agencies. Individuals were classified as 'list-identified' if originally contacted via lists, or 'self-identified' if contacted through advertising campaign.
Note: A total of 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”
Baseline interviews were conducted between September 2003 and November 2004 (2-3 years post-9/11). Of 71,437 interviews, 67,527 (95%) were completed using CATI and 3,910 using CAPI. Questionnaire was administered in four languages: English (95.2%), Spanish (1.9%), Cantonese (1.5%), and Mandarin (1.0%).
Note: A translation service provided by a vendor was used for languages other than the four pretranslated languages (n=315). Interviewers took actions if respondent showed emotional distress. A total of 3,100 proxy interviews were completed.
“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)”
Informed consent was obtained from all participants. Eligibility was determined based on the four broad eligibility groups and exposure criteria.
Note: The WTCHR protocol was approved by IRBs of CDC and NYC DOHMH in 2003. A Federal Certificate of Confidentiality was obtained.
“The interview included: (a) informed consent; (b) determination of eligibility”
Demographic information was collected along with contact information for follow-up, including information on up to three people likely to know future whereabouts of respondent.
Note: N/A
“(c) 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)”
General exposure questions were asked regarding dust and debris cloud exposure. Specific exposure assessment sections were administered for each of the four eligibility groups, including questions about work sites, dates, activities, evacuation, and return dates.
Note: Time periods for analysis were based on meteorological data including rainfall dates (September 14 and 19, 2001) and fire extinguishment date (December 19, 2001)
“(e) general exposure questions (e.g., to the dust and debris cloud); (f) specific exposure assessment sections for each of the four eligibility groups”
Enrollees were asked about injuries sustained on 9/11 ranging from eye injury or irritation to fractures, burns and concussions.
Note: N/A
“(g) 9/11 injuries; (h) physical health symptoms and conditions before and after 9/11”
Enrollees were asked about physical health outcomes including: (a) injuries on 9/11; (b) new or worsening respiratory symptoms after 9/11; (c) new or worsening nonrespiratory symptoms; and (d) specific conditions diagnosed by physician in 2-3 years after 9/11 including newly diagnosed asthma, emphysema, hypertension, coronary heart disease, angina, heart attack, diabetes, stroke, and cancer.
Note: Questions about symptoms were similar to well-tested examples used in the 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”
Mental health outcomes included serious psychological distress (SPD) in the 30 days prior to interview, assessed using the Kessler-6 scale (K-6). Respondents scoring above cutoff of 13 on K-6 were classified as having current SPD.
Note: K-6 is correlated with diagnostic measures of major depressive disorder, generalized anxiety disorder, schizophrenia, and other mental disorders
“Mental health outcomes included probable posttraumatic stress disorder (PTSD) and serious psychological distress (SPD) in the 30 days prior to the interview. The Kessler-6 scale (K-6), used to determine SPD, is a psychometrically validated, epidemiologic screening measure”
The PTSD-Checklist Civilian Version (PCL), a 17-item symptom scale corresponding to DSM-IV criteria, was administered to adults. Overall prevalence of current probable PTSD was calculated using sum of item responses with cutoff of 44.
Note: PCL has been validated for use with 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”
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.
Note: For children under 18 years at time of interview, parents and guardians served as proxies (n=2,635)
“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”
Enrollees were asked about geographic location when they first encountered the dust cloud using locator variables: street address (n=15,167), closest cross street intersection (n=11,329), closest landmark (n=10,732), and closest subway stop (n=1,119). Geocoding occurred only if enrollee answered yes to being caught in dust cloud.
Note: DCP's Geosupport application was used for automated batch matching of street addresses. LION geodatabase was used for geocoding intersections and manual address matching.
“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)”
A standard deviational ellipse was constructed, centered on the mean center of all geocodable locations reported by enrollees when they first encountered the dust cloud, with long axis in direction of maximum dispersion and short axis in direction of minimum dispersion.
Note: The 1 and 2 standard deviational ellipses correspond to 68.2% and 95.4% of the geocoded data, respectively
“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”
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.
Note: Chi-square and Cochran-Armitage tests were used to determine statistical significance
“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”
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.
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”
To construct estimates of total number of adults eligible for WTCHR who experienced illness or symptoms, prevalence of self-reported health problems among enrollees was applied to estimates of total exposed persons. All exposed adults were categorized into three mutually exclusive hierarchical categories: rescue/recovery workers, building occupants/passersby/people in transit, and residents south of Canal Street.
Note: Three estimates were calculated: midpoint (based on list-identified prevalence), upper bound (based on self-identified prevalence), and lower bound (assuming 50% higher enrollment among symptomatic list-identified persons). Estimates were rounded to nearest hundred.
“To construct estimates of the total number of adults eligible for the WTCHR who experienced illness or symptoms after the attacks, the prevalence of self-reported health problems among enrollees was applied to estimates of the total number of persons exposed for each enrollee category”
Enrollees meeting eligibility criteria based on proximity to WTC attack by time and place, acute exposure to dust/debris cloud, or chronic exposure to smoke/fumes. Four eligibility groups: (a) people present south of Chambers Street in lower Manhattan on 9/11; (b) rescue/recovery/cleanup workers at WTC site or related locations; (c) residents south of Canal Street; (d) students and staff at schools south of Canal Street