Surveillance of occupational lung diseases in Canada

S ur veil lance of dis ease usu ally re fers to the “on go ing scru tiny of all as pects of oc cur rence and spread of a dis ease that are per ti nent to ef fec tive con trol” (1). The pri mary goal of a sur veil lance pro gram of oc cu pa tional dis eases is to moni tor trends or pat terns of a health event or of risk fac tors, with the aim of im ple ment ing and as sess ing the ef fi cacy of in ter ven tions. Cur rently there is no com pre hen sive sur veil lance pro gram D -W , GR C ONTRE RAS , R R OUS SEAU , M C HAN -Y EUNG . Sur veil lance of oc cu pa tional lung dis eases in Can ada. Can Respir J 1996;3(5):291- 294. Sur veil lance pro grams for oc cu pa tional lung dis eases are re viewed, with ref er ence to a two- year pi lot study that was un der taken in the prov ince of Brit ish Co lum bia. Mem bers of the Brit ish Co lum bia Tho racic So ci ety were in vited to par tici pate by re port ing any new cases of oc cu pa tional lung dis ease in each two- month pe riod. Par tici pat ing phy si cians re sponded well dur ing the first year of the pi lot study, but longer term com mit ment was dif fi cult to main tain. It is rec om mend that phy si cians be edu cated, start ing in medi cal school, about the rec og ni tion and di ag no sis of oc cu pa tional dis eases and the im por tance of sur veil lance of chronic dis eases. The authors en cour age, at least on a trial ba sis, a na tion ally based sur veil lance pro gram of oc cu pa tional lung dis eases.

Sur veil lance pro grams for oc cu pa tional lung dis eases are re viewed, with ref er ence to a two-year pi lot study that was un der taken in the prov ince of Brit ish Co lum bia. Mem bers of the Brit ish Co lum bia Tho racic So ci ety were in vited to par tici pate by re port ing any new cases of oc cu pa tional lung dis ease in each two-month pe riod. Par tici pat ing phy si cians re sponded well dur ing the first year of the pi lot study, but longer term com mit ment was dif fi cult to main tain. It is recom mend that phy si cians be edu cated, start ing in medi cal school, about the rec og ni tion and di ag no sis of oc cu pa tional dis eases and the im por tance of sur veil lance of chronic diseases. The authors en cour age, at least on a trial ba sis, a nation ally based sur veil lance pro gram of oc cu pa tional lung dis eases.

Key Words: Lung dis eases, Oc cu pa tional dis eases, Sur veil lance
Sur veil lance des pneu mo pathies pro fes sion nelles au Can ada RÉS UMÉ : Les pro grammes de sur veil lance des pneu mopathies pro fes sion nelles sont pas sés en re vue, suite à une étude pi lote de deux ans qui a été menée en Colombie-Britannique. Les mem bres de la So ci été de tho ra colo gie de la Colombie-Britannique ont été in vi tés à par ti ci per à cette étude en rap por tant tous les nou veaux cas de pneu mopathies pro fes sion nelles tous les deux mois. Les médecins par tici pants ont bien rap porté les données pen dant la première an née de l'étude pi lote, mais leur con tri bu tion a été dif fi cile à main tenir à plus long terme. On re com mande que, dès le dé but de leurs études de médecine, les médecins ap pren nent à re con naître et à di ag nos tiquer les pneu mopathies pro fes sion nelles, et à ap pré cier l'im por tance de la sur veil lance des mala dies chroniques. Les au teurs en couragent, au moins à ti tre d'es sai, un pro gramme de sur veil lance des mala dies pro fes sion nelles d'en ver gure na tion ale.
of oc cu pa tional dis eases in Can ada. Spiegel and Yassi (2) gave an ex cel lent re view on the po ten tial use ful ness of various Ca na dian data sources, such as health in sur ances claims, hos pi tal sepa ra tion forms, and pro vin cial and na tional health reg is tries, for the sur veil lance of oc cu pa tional dis ease. An alter na tive data source is in for ma tion on dis eases, in ju ries and deaths that are rou tinely col lected by the pro vin cial work ers' com pen sa tion boards (WCB). WCB data are com pre hen sive for the work ing popu la tion and re quire strict di ag nos tic cri teria for ac cep tance. How ever, there is a lack of stan dardi zation, and the data are in com plete be cause they are based on 'a ccepted claims' in which early in di ca tions of dis ease are not rec og nized; there is also a hesi tancy by po ten tial claimants and phy si cians to be come in volved in the bu reauc racy.
Re port ing by phy si cians or other health care pro vid ers can pro vide a valu able method for sur veil lance of oc cu pa tional dis eases. An ad van tage to us ing phy si cians' re ports is that they are gen er ally avail able in a more timely way than reg istry data, which is par ticu larly im por tant when case re ports are used to di rect in ter ven tion ef forts in in di vid ual cases. By es tab lish ing a sys tem for re port ing speci fied dis eases, phy sicians can be a re source for re port ing un usual cases or clus ters that may be of pub lic health con cern. At pres ent there is no such sys tem in Can ada for the re port ing of oc cu pa tional lung dis eases.
To as sess the fea si bil ity of es tab lish ing an oc cu pa tional lung dis eases reg is try, a pi lot study was con ducted in Brit ish Co lum bia based on vol un tary re port ing by phy si cians.

PILOT OCCUPATIONAL LUNG DISEASES
REGISTRY IN BRITISH COLUMBIA The pi lot study was con ducted be tween 1991 and 1992 using a method simi lar to that used by the Sur veil lance of Work Re lated Oc cu pa tional Res pi ra tory Dis ease (SWORD) project (3), with some modi fi ca tions. De tails of the first year of this pi lot study have been re ported pre vi ously (4). All par ticipants were mem bers of the Brit ish Co lum bia Tho racic So ciety and in cluded res pi rolo gists and a number of gen eral prac ti tio ners and in ter nal medi cine phy si cians with in ter est in res pi ra tory dis eases, lo cated in dif fer ent re gions of Brit ish Co lum bia. The popu la tion in the lo cal health ar eas served by the par tici pat ing phy si cians rep re sented 81.5% of the to tal labour force in Brit ish Co lum bia. The 68 par tici pants were asked to re port, every two months, new cases of res pi ra tory ill ness that they be lieved to be at trib uted to work ex po sure. At the end of two months they were asked to re turn the cards and they re ceived new ones for the next pe riod. The im portance of re turn ing all cards, even with no case re port, was em pha sized. Phy si cians who did not re turn the card at the end of the re port ing pe riod were con tacted by let ter or by telephone. To avoid du pli ca tion of re ports, the pa ti ent's sur name and first ini tial, sex, age, city or town of resi dence, job, type of in dus try where he or she was work ing and the sus pected agent pro vok ing the dis ease were also re corded. The re porting card had a di ag nos tic clas si fi ca tion of the most fre quently en coun tered oc cu pa tional lung dis eases. A brief re port of the pre vi ous re port ing pe riod was dis trib uted to the par tici pat ing phy si cians to gether with the new cards.
As shown in Fig ure 1, dur ing the first half of the first year of this proj ect, the rate of re turn of re port ing cards was 80%. By the end of the first year the number de creased to 67%; at the end of the sec ond year the rate was only 33%. Dur ing the first year, 66.7% of the par tici pat ing phy si cians re turned five to six cards, and 1.4% did not re turn any cards. Dur ing the sec ond year, the cor re spond ing fig ures were 49.3% and 20.3%, re spec tively (Fig ure 2).
In 1991, 246 new cases of oc cu pa tional lung dis eases were re ported by the par tici pat ing phy si cians. In the same year, the WCB of Brit ish Co lum bia ac cepted 319 claims for oc cu pa tional lung dis ease. The dis crep ancy is re lated to differ ences in the popu la tion cov ered and of di ag no sis and report ing cri te ria. In the reg is try, the larg est di ag nos tic group was oc cu pa tional asthma, ac count ing for 50% of all re ported cases, fol lowed by asbestos-related dis eases (32%), chronic ob struc tive pul mo nary dis eases (4.5%) and lung can cer (2.8%). Phy si cians re ported 40 cases of meso the lioma in 1991 but none was re ported by the WCB of Brit ish Co lumbia. One hun dred and twenty-four cases of work-related asthma were re ported to the reg is try, while the WCB accepted only 43 such new cases. Con versely, only three cases of in ha la tion ac ci dents were re ported by phy si cians to the reg is try while 208 cases were ac cepted by the WCB. In British Co lum bia, most in ha la tion ac ci dents are re ported di rectly to the WCB by work ers, and the claims are usu ally ac cepted with out a medi cal cer tifi cate.
Our pi lot study showed that the reg is try was suc cess ful dur ing the first year, as dem on strated by the rate of re turn of re port ing cards. The in ci dence of oc cu pa tional lung dis eases of 181 per mil lion re ported dur ing the first year was twice that re ported by the SWORD proj ect in the United King dom (3). How ever, two-thirds of the phy si cians failed to file records at the end of two years; in ter est in the proj ect was dif ficult to main tain, es pe cially for phy si cians who had not en coun tered a case of oc cu pa tional lung dis ease dur ing the study pe riod.

OCCUPATIONAL LUNG DISEASES SURVEILLANCE
The pi lot proj ect was based on the strate gies used by the SWORD proj ect ini ti ated in the United King dom in 1989 (3). Mem bers of the Brit ish Tho racic So ci ety and the So ci ety of Oc cu pa tional Medi cine were asked to re port to the proj ect any newly di ag nosed res pi ra tory ill ness that they be lieved was due to oc cu pa tional or work-related ex po sure, and all par tici pants re ceived monthly feed back. Oc cu pa tional asthma was found to be the most com monly re ported oc cu pational lung dis ease. The re sults of the proj ect were com pared with data con cern ing those who re ceived dis able ment benefits. The fig ures from the two sources were simi lar for as besto sis, lung can cer and byssi no sis, but the fig ure for oc cu pa tional asthma (554 cases) con trasted to the of fi cial fig ure of 222 cases based only on agents for which dis abil ity bene fits are pay able. It was sug gested that the true fre quency of acute oc cu pa tional res pi ra tory dis eases might be three times greater than has been re ported through out tra di tional sources such as the use of work ers' com pen sa tion and employ ers' rec ords. While the rate of par tici pa tion of in vited chest phy si cians in the SWORD proj ect dur ing the first year was 83%, the rate of re turn of the re port ing cards by phy sicians dur ing the fol low ing years has not been re ported (5).
The United States Na tional In sti tute for Oc cu pa tional Safety and Health (NIOSH) has es tab lished the Sen ti nel Event No ti fi ca tion Sys tem for Oc cu pa tional Risks (SEN -SOR) pro gram as a model sur veil lance pro gram based on health pro vider rec og ni tion and no ti fi ca tion (6). The SEN -SOR pro gram has four com po nents: a set of se lected tar get con di tions; a net work of sen ti nel health care pro vid ers; a surveil lance cen tre that re ceives and ana lyzes re ports; and work site in ter ven tion ac tiv ity that is guided by sur veil lance data. A sen ti nel oc cu pa tional health event most suited to health care pro vider re port ing and in ter ven tion is oc cu pa tional asthma. How ever, un der re port ing is a per sis tent prob lem, with the low rate of phy si cian par tici pa tion be ing cited as one of the most im por tant lim it ing fac tors in the proj ect. Cali fornia has es tab lished a state wide sur veil lance of oc cu pa tional asthma (7) us ing the 'Do ctor's first re port of oc cu pa tional injury of ill ness', which are filed with pri vate, state-run and self-insured work ers' com pen sa tion in sur ance car ri ers. In the first year of the study, there were 330 re ports of physiciandiagnosed asthma. Of those cases in ves ti gated fur ther, 27% had work-aggravated asthma, while 47% were sus pected of hav ing oc cu pa tional asthma.
In the United States, a sur vey con ducted in 1985 (8) showed that 32 states had pro grams for re port ing oc cu pational ill nesses by one or more sources. In 16 states, le gal pen al ties ex isted for non re port ing. De spite this, un der re porting by phy si cians in these states was com mon. Rea sons for the fail ure of re port ing by phy si cians in cluded the fol low ing: lack of guid ance as to what con di tions to re port or what cri teria should be used for re port ing oc cu pa tional lung dis eases; lack of train ing to rec og nize oc cu pa tional dis eases and a percep tion that oc cu pa tional dis ease re port ing is use less compared with re port ing in fec tious dis ease; and re luc tance to be come in volved with the WCBs or with liti ga tion. Regulation-enforced re port ing has been suc cess fully dem onstrated in Fin land (9). For over 30 years, the In sti tute of Occu pa tional Health in Fin land has had a reg is ter of oc cu pa tional dis eases in which phy si cians are re quired by law to re port every case of oc cu pa tional dis ease or dis ease related to work. Data are re ceived from three sources: re ports of oc cu pa tional dis ease filed by pro vin cial medi cal of fi cers; ac ci dent re ports and di ag no ses sub mit ted by in sur ance compa nies; and cases di ag nosed at the In sti tute of Oc cu pa tional Health. A com pari son of 1989 re turns showed that the reported in ci dence of oc cu pa tional asthma in Fin land was six times higher than that in the United King dom.

DISCUSSION
Par tici pat ing phy si cians were en cour aged to re port cases that they thought were most likely to be due to oc cu pa tional ex po sure. Com pari son be tween the pi lot reg is try study and the data from the WCB showed lit tle dis crep ancy in the in cidence of as bes to sis and sili co sis, but con sid er able dis crepancy in the in ci dence of oc cu pa tional asthma. Not only is the di ag no sis of oc cu pa tional asthma less well un der stood, many phy si cians do not have the fa cili ties to con firm the di ag no sis by ob jec tive means.
In gen eral, the case defi ni tions used for com pen sa tion pur poses are stricter, while the case defi ni tions for sur veillance pro grams may be less spe cific but more sen si tive if the pur pose of the sur veil lance pro gram is to trig ger a more detailed in ves ti ga tion. There fore, it is im por tant to de fine the pur pose of the sur veil lance pro gram if a reg is try is to be set up.
Can an oc cu pa tional lung dis ease sur veil lance pro gram be mounted suc cess fully in Can ada? A volunteer-based sur veillance pro gram is vul ner able to un der re port ing and even tual drop-out. Un der such a sys tem, a one-time 'sna pshot' of the na tional in ci dence of oc cu pa tional lung dis ease is pos si ble. Longer term secu lar trends would be much more dif fi cult to es tab lish. Even with a na tional regulation-enforced sys tem, un der re port ing could still be a prob lem. The key to es tab lishing a suc cess ful reg is try lies in the bet ter edu ca tion of phy sicians, start ing in medi cal schools, on the rec og ni tion and di ag no sis of oc cu pa tional dis eases as well as the im por tance of re port ing to ap pro pri ate agen cies for pre ven tive meas ures. Com mu ni ca tion of re search to prac tis ing phy si cians is an impor tant part of the pro cess. For ex am ple, there is in creas ing evi dence of an as so cia tion be tween chronic ob struc tive pulmo nary dis ease and ex po sure to many dif fer ent types of in organic and or ganic dusts, be yond any ef fect due to smok ing (10).
A volunteer-based na tional oc cu pa tional lung dis eases pro gram co or di nated by a net work of aca demic cen tres could pro vide valu able in for ma tion on trends in dis ease and improve upon the pos si bili ties of early de tec tion to al low for in -ter ven tion. An ad di tional bene fit of a na tional sur veil lance pro gram would be the ex panded aware ness and edu ca tional op por tu ni ties for the health care com mu nity re gard ing the na ture and im pact of oc cu pa tional lung dis eases.

AC KNOW LEDGE MENTS:
This work was sup ported by the Brit ish Co lum bia Lung As so cia tion and the Work ers' Com pen sation Board of Brit ish Co lum bia. The authors thank all phy si cians who par tici pated in the reg is try for their dedi ca tion and pa tience in sub mit ting the re port ing cards regu larly, and Dr JC McDon ald for his ad vice in set ting up the reg is try.