Webber et al. Multivariate analyses. Multivariate logis- models satisfied Hosmer-Lemeshow goodness approximately four times their pre-9/11 rate. tic regression models in the cohort predict- of fit tests (Tables 3–5). Other LRS rates after 9/11 remained relatively ing symptoms at year 4, either persistent or constant, and by study’s end, wheeze and Discussion delayed onset were carried out separately for dyspnea were reported at 28.6 and 15.5 times LRS, URS, and GERD outcomes. Arrival In this study we describe the prevalence of their pre-9/11 rates, respectively. group, initial symptoms, age on 9/11, and respiratory symptoms in a well-characterized For URS, the prevalence of sore throat months of work (either modified by mask/ group of 10,378 WTC-exposed firefighters declined by 41%, whereas rhinosinusitis respirator use or unmodified) were indepen- who worked, on average, four times longer at symptoms increased by 6%. The final rates dently associated with symptoms at follow-up the WTC site (Wheeler et al. 2007) and were were 10.7 and 10.6 times their pre-9/11 rates, in all models. We used the unmodified dura- followed more than twice as long (4 years) as respectively. GERD symptoms increased tion variable because results did not dif- workers in most previous reports (Buyantseva by 3.2% during the study, with a final rate fer from those using the modified variable. et al. 2007; Tao et al. 2007; Wheeler et al. 8.2 times its pre-9/11 prevalence. We are Elapsed time between year 1 and year 4 ques- 2007). We found that cough, previously confident that comparing rates during the tionnaires remained significant only in the characterized in air pollution studies as the final study period with pre-9/11 rates is valid LRS model. Three interaction terms—months most sensitive indicator of lower respiratory even though the latter were collected retro- of work and arrival group, smoking and insult (Dockery and Pope 1994), similarly spectively at the first post-9/11 question- arrival group, and months of work and mask/ served as a sentinel indicator in WTC-exposed naire, because these data are comparable with respirator use—were not statistically signifi- firefighters. In our study, cough was one of information collected during FDNY periodic cant (all p > 0.05). The overlap between LRS, the earliest-appearing and earliest-resolving medical evaluations obtained pre-9/11. URS, and GERD was apparent, especially in symptoms, declining sharply between 1 and Analyses of the cohort of 3,722 enabled the model predicting GERD, where the addi- 2 years post-9/11 to affect 16% of firefighters us to examine reported-symptom progres- tion of terms for initial LRS and rhinosinusitis by the study’s end. Despite this sharp decline, sion in the group of firefighters who com- symptoms greatly improved the model fit. All cough rates during the final period were pleted questionnaires in both the first and Table 2. Symptom progression [no. (%)] by arrival group in the cohort (n = 3,722) at year 4. Arrival group 1 2 3 4 Total Symptom pattern (n = 603) (n = 2,504) (n = 384) (n = 231) (n = 3,722) p-Valuea Cough Early onset /recover 260 (43.1) 1,014 (40.5) 136 (35.4) 67 (29.0) 1,477 (39.7) < 0.0001 Persistent 104 (17.3) 297 (11.9) 39 (10.2) 9 (3.9) 449 (12.1) < 0.0001 Delay onset 20 (3.3) 105 (4.2) 13 (3.4) 7 (3.0) 145 (3.9) 0.77 Asymptomatic 219 (36.3) 1,088 (43.5) 196 (51.0) 148 (64.1) 1,651 (44.4) < 0.0001 Wheeze Early onset /recover 64 (10.6) 284 (11.3) 48 (12.5) 25 (10.8) 421 (11.3) 0.64 Persistent 156 (25.9) 446 (17.8) 42 (10.9) 11 (4.8) 655 (17.6) < 0.0001 Delay onset 103 (17.1) 445 (17.8) 51 (13.3) 35 (15.2) 634 (17.0) 0.15 Asymptomatic 280 (46.4) 1,329 (53.1) 243 (63.3) 160 (69.3) 2,012 (54.1) < 0.0001 Dyspnea Early onset /recover 81 (13.4) 319 (12.7) 43 (11.2) 22 (9.5) 465 (12.5) 0.09 Persistent 207 (34.3) 558 (22.3) 63 (16.4) 19 (8.2) 847 (22.8) < 0.0001 Delay onset 95 (15.8) 441 (17.6) 54 (14.1) 31 (13.4) 621 (16.7) 0.23 Asymptomatic 220 (36.5) 1,186 (47.4) 224 (58.3) 159 (68.8) 1,789 (48.1) < 0.0001 Any LRS Early onset /recover 138 (22.9) 602 (24.0) 107 (27.9) 50 (21.7) 897 (24.1) 0.58 Persistent 315 (52.2) 1,016 (40.6) 112 (29.2) 45 (19.5) 1,488 (40.0) < 0.0001 Delay onset 40 (6.6) 245 (9.8) 42 (10.9) 29 (12.6) 356 (9.6) 0.004 Asymptomatic 110 (18.2) 641 (25.6) 123 (32.0) 107 (46.3) 981 (26.4) < 0.0001 Rhinosinusitis Early onset /recover 91 (15.1) 395 (15.8) 63 (16.4) 36 (15.6) 585 (15.7) 0.71 Persistent 202 (33.5) 722 (28.8) 95 (24.7) 39 (16.9) 1,058 (28.4) < 0.0001 Delay onset 126 (20.9) 520 (20.8) 63 (16.4) 44 (19.1) 753 (20.2) 0.17 Asymptomatic 184 (30.5) 867 (34.6) 163 (42.5) 112 (48.5) 1,326 (35.6) < 0.0001 Sore throat Early onset /recover 184 (30.5) 771 (30.8) 128 (33.3) 60 (26.0) 1,143 (30.7) 0.60 Persistent 229 (38.0) 748 (29.9) 80 (20.8) 36 (15.6) 1,093 (29.4) < 0.0001 Delay onset 49 (8.1) 208 (8.3) 26 (6.8) 22 (9.5) 305 (8.2) 0.93 Asymptomatic 141 (23.4) 777 (31.0) 150 (39.1) 113 (48.9) 1,181 (31.7) < 0.0001 Any URS Early onset /recover 132 (21.9) 583 (23.3) 104 (27.1) 51 (22.1) 870 (23.4) 0.35 Persistent 332 (55.1) 1,182 (47.2) 148 (38.5) 61 (26.4) 1,723 (46.3) < 0.0001 Delay onset 57 (9.5) 272 (10.9) 44 (11.5) 38 (16.5) 411 (11.0) 0.008 Asymptomatic 82 (13.6) 467 (18.7) 88 (22.9) 81 (35.1) 718 (19.3) < 0.0001 GERD Early onset /recover 80 (13.3) 335 (13.4) 42 (10.9) 28 (12.1) 485 (13.0) 0.35 Persistent 217 (36.0) 628 (25.1) 71 (18.5) 27 (11.7) 943 (25.3) < 0.0001 Delay onset 110 (18.2) 461 (18.4) 70 (18.2) 47 (20.4) 688 (18.5) 0.59 Asymptomatic 196 (32.5) 1,080 (43.1) 201 (52.3) 129 (55.8) 1,606 (43.2) < 0.0001 ap-Values from Cochran–Armitage test for trend. 978 117 | number 6 | June 2009 • Environmental Health Perspectives ovlume