1 IN T R N A T I N A L J U R N A L F U P A T I N A L S A F T Y A N D R G N M I S 2, V L. 6, N. 2, The Indigenus Fisherman Divers f Thailand: Diving-Related Mrtality and Mrbidity David Gld Internatinal Labur ffie, Geneva, Switzerland Alan Geater Prine f Sngkla University, Hatyai, Thailand Smbn Aiyarak Phuket Prvinial hief Medial ffie, Phuket, Thailand Smhai Wngharenyng Ranng Prvinial Health ffie, Ranng, Thailand Wilawan Juengprasert Ministry f Publi Health, Bangkk, Thailand Mark Jhnsn Stke Mandeville Hspital, Aylesbury, Bukinghamshire, UK Paul Skinner West Middlesex University Hspital, Islewrth, Middlesex, UK The Urak Lawi are indigenus fishermen n Thailand s west ast. The ppulatin inludes an estimated 4 divers wh dive using surfae-supplied mpressed air. In a rss-setinal survey nduted amng the 6 majr mmunities f Urak Lawi, questinnaire-based interviews were administered t ative divers, ex-divers, and families r lleagues f divers wh had died in the previus 5 years. Six deaths resulting frm diving-related aidents were identified, indiating a diving-related mrtality rate f apprximately 3 per 1, persn-years, while in the same 5-year perid 11 divers had been disabled wing t diving-related events, indiating a diving-related disabling event rate f apprximately 55 per 1, persn-years. Amng 342 ative divers interviewed, ne third reprted having suffered frm dempressin illness, althugh based n reprted urrent symptms ver 5% were lassified as suffering frm reurring nn-disabling dempressin illness. Physial examinatin nduted n a subset f 98 ative divers revealed the presene f spinal injury (lnus, raised musle tne, and heightened reflexes) and f jint damage (pain in ne r mre jint, repitus, r restrited mvement) in 24 and 3% respetively. Imprved primary preventin and medial treatment are needed t redue mrtality and mrbidity amng this ppulatin. indigenus divers Thailand mrtality mrbidity dempressin illness
2 148 D. GLD T AL. 1. INTRDUTIN A grup f 4 men between the ages f 11 and 62 earn their living by diving using mpressrs t gather fish, seashells, and ther marine prduts n Thailand s west ast. A researh prjet, in partnership with the Ministry f Publi Health, has been ative sine 1996 addressing the upatinal safety and health risks assiated with this ativity. The target ppulatin is a grup f indigenus fishermen divers knwn as the Urak Lawi (Gld, Geater, Aiyarak, Wngharenyng, & Juengprasert, 2). The Urak Lawi, alng with anther grup f indigenus peple living t the nrth f Phuket, are knwn as the Sea Gypsies. The Urak Lawi live in nine villages in three prvines between Phuket Island and the brder with Malaysia. As sme f the villages are quite small, with fewer than 1 divers, the prjet has reated six gegraphial grupings r mmunities, three in Phuket Prvine, ne in Krabi Prvine, and tw in Satun Prvine. There are apprximately 4 ative divers at any ne time based n interviews f heads f all villages. nly males dive. They nrmally start diving when they finish mpulsry eduatin and ntinue t dive until the age f 5 unless they are unable t d s (Gld et al., 2). asual bservatins in the Urak Lawi villages reveal a number f wrking-age men with varius degrees f physial disability. These disabilities are nsistent with the knwn effets f dempressin illness, suggesting The pinins and assertins ntained within this artile shuld nt be nstrued as representing thse f the Internatinal Labur ffie. The authrs wish t express their thanks t the village hiefs and divers wh submitted t the interview and physial examinatin; the hief prvinial medial ffiers in the prvines f Phuket, Krabi, and Satun; the prvinial, distrit and sub-distrit health are wrkers fr arrying ut the surveys; the Hyperbari Medial mmittee and the upatinal Health Divisin f the Ministry f Publi Health f Thailand; Dr. Kari Kurppa, Dr. Markku Mattila, and Mr. Teuv Uusital fr their guidane in setting up the prjet; Dive-Safe Asia, Dr. Maurie rss, and Mr. Rihard Dawsen f the Divers Diseases Researh entre f the UK, the Ryal Thai Navy s Undersea Medial Divisin, Dr. Rihard Mn, Dr. Rihard Vann, and Mr. Jel Dvenbarger f the Divers Alert Netwrk, USA, Dr. David llitt, Dr. Rbert Wng, Dr. Mihael Lepawsky, and Ms. hinda Saengharnhai fr assistane and guidane; Drs. Mihael Ryan and Thmas Grein at the WH fr assistane in data analysis; and Dr. Jukka Takala and Ms. Ratna DeSilva fr assistane in reviewing the manusript. The pidemilgy Unit, Prine f Sngkla University, is partially supprted by the Thailand Researh Fund. rrespndene and requests fr reprints shuld be sent t David Gld, hemin des erfs, 1272 Genlier/VD, Switzerland. -mail: bluewin.h.
3 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 149 that upatin-related mrbidity may be frequent amng this ppulatin and a pssible mmn ause f mrtality and mrbidity. Hwever, there are n registries f divers, injuries, diseases, r deaths fr this minrity ppulatin. Therefre this study sught t dument the prevalene f diving-related mrbidity and estimate diving-related mrtality rates amng divers within this ppulatin. A subsidiary bjetive was t link diving praties with reurring mrbidity amng urrent divers. 2. MTHDS Infrmatin regarding mrtality and mrbidity amng the target ppulatin was btained using questinnaire-based interviews and physial examinatin between 1996 and Sampling Three subsets f the diving ppulatin were examined: ative divers, ex-divers wh had stpped diving as a result f diving-related disability, and divers wh had died due t diving-related aidents r illness. It was attempted t reruit all urrently ative divers in six mmunities (Rawai, Kh Siray, and Sapam in Phuket Prvine; Kh Lanta in Krabi Prvine; Kh Li Peh and Kh Buln in Satun Prvine) int the study. This was dne during repeated visits t eah mmunity by lal healthare wrkers with the assistane f the village heads and diving bat wners r leaders. Mrtality. T asertain a histry f diving and death within this ppulatin, it was neessary t first determine wh had died, whether r nt the deeased was a diver, and whether r nt the death was diving-related. With infrmatin asertained frm the hief f the village, the healthare wrkers interviewed the family r lleagues f males ver the age f 11 wh had died within the 5 years prir t the survey within the six mmunities. Disabling mrbidity. The health are wrkers, thrugh the hiefs f villages and dive leaders, sught ut thse males wh had been diving using a mpressr but had stpped. Mrbidity. The entire sample f urrent mpressr-divers was used t identify mrbidity that was nt suffiient t ause the diver t stp diving at the time f the study.
4 15 D. GLD T AL. Physial examinatin. A physial examinatin was nduted n an availability subset f 98 urrently ative divers identified in Rawai, Kh Siray, Sapam, and Kh Lanta mmunities ver a l-mnth perid Questinnaires Based n field bservatins, a series f fur questinnaires was designed, translated, and pilted fllwing a Wrld Health rganizatin (WH) methdlgy (Lutz, halmers, Hepburn, & Lkerbie, 1992). Separate questinnaires were develped t eliit respnses frm hiefs f villages, ative divers, disabled divers, and the family r -wrkers f deeased divers. In all questinnaires, mst f the questins were lsed and a few pen. ther questins were bth pen and lsed, that is, the interviewer had the ability t fill in a respnse that was different frm the given respnses (Lutz et a l 1 992). Sixteen healthare wrkers frm the prvinial medial ffies and the subdistrits and villages where the Urak Lawi reside were trained in administering the questinnaire. These healthare wrkers were seleted, as they are nrmally well aware f the health patterns within the village. All interviews were nduted in the Thai language. The questinnaires addressed sme basi demgraphi infrmatin, diving praties, awareness f risk and attitudes twards risk, and the mrbidity f dempressin illness, whih is defined as dempressin sikness and pressure-related injuries r bartrauma. Diving praties (Gld et al., 2a), issues related t attitudes and awareness f hazards (Gld et al., 2b), and eduatinal and infrmatinal interventins (Gld et al., in press) are addressed in separate papers Identifiatin f Diving-Related Mrtality As the Urak Lawi are indigenus peple living in rural villages, pst-mrtem examinatin is unmmn. In defining diving-related deaths, ertain linial signs and symptms that are diretly related t diving praties and nt nrmally fund in the ppulatin were used. ah death was nsidered arding t auses r reprted signs and symptms likely t be diving-related. The irumstanes surrunding eah death were examined in rder t determine thse that were diving-related. These inluded paralysis and sudden death.
5 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND Identifiatin f Diving-Related Disabling Mrbidity Village and subdistrit health-are wrkers, knwledgeable abut disabled individuals in the villages, wrked with the village hiefs t identify divers wh had stpped diving due t disabling mrbidity resulting frm diving. Thse wh had never used a mpressr r thse wh were injured by mehanisms ther than diving were exluded. With a view t differentiating between divers wh had suffered serius mrbidity and divers wh had stpped diving fr ther reasns, if the diver indiated he had hanged jbs (fr reasns ther than injury r illness resulting frm diving) r had nt had any diffiulty when diving, he was nt nsidered as part f the grup f disabled divers. Fr this grup, the definitin f disabling mrbidity inludes ases where diving has led t a nditin inluding paralysis, diffiulty in breathing, blurred visin, headahes, and ther manifestatins assiated with dempressin illness as a nsequene f whih a diver uld n lnger dive. By subtrating the year the diver stpped diving frm the diver s age, the age at whih injury was sustained uld be estimated Identifiatin f Diving-Related Mrbidity Amng Ative Divers Interview Divers were asked several questins abut seleted signs and symptms relative t diving-related illness. The fllwing areas were explred: whether the diver ften experiened jint pain, tingling, lss f sensatin, r inability t mve as a result f his diving, and whether the diver had ever experiened and revered frm dempressin illness. (Within this ppulatin, dem pressin illness refers t a situatin leading t paralysis, unnsiusness, r ther severe signs and symptms [Aiyarak, 1991]). A mpsite utme variable fr the presene f reurring, nn-disabling dempressin illness was reated and rss-tabulated against variables related t demgraphis, experiene, and praties. The mpsite variable was nstruted as fllws: Frequent inability t mve r frequent weakness as a result f diving was lassified as prbable; frequently experiening pain r tingling r lss f sensatin r ne-sided weakness but nt weakness r inability t mve was lassified as suspeted; and nne f the abve manifestatins was listed as nt suspeted. A variable ranking f the expeted risk f
6 152 D. GLD T AL. develping dempressin illness was reated arding t the mdel prpsed by Gerth and Vann (1996) using the reprted pattern f diving n the last day f diving Physial examinatin Tw senir medial students frm the United Kingdm, under the supervisin f the Ministry f Publi Health, arried ut physial examinatins. The results f the assessment were later verified by a fllw-up examinatin f a number f seleted examinatins n the basis f available divers in tw villages by an experiened diving medial pratitiner. The physial examinatin inluded the tympani membrane, an examinatin f shulder, hip, knee, and ankle jints fr pain, repitus, and restrited mvement, lwer limb neurlgy, lnus, lwer limb pwer, reflexes, sensatin, and rdinatin. The physial examinatin data were used t grup divers int tw mrbidity ategries: damage t jints and spinal injury. A mpsite variable f jint damage was develped in whih the presene f pain n mvement, repitus, r restrited mvement in mre than ne jint indiated diving-related jint damage. Spinal injury was assessed by the presene f lnus, inreased tne, and heightened reflexes. A mpsite variable was develped in whih the presene f any f the three NS (entral nervus system)-related signs indiated ptential entral nervus system damage Statistial Analysis Results were analyzed using pi Inf 6 (Dean et al., 1995) and STATA 5. (Stata rpratin, 1997) sftware. During analysis, the pen questins were lsed by gruping respnses. rude (bivariate) dds ratis and 95% nfidene intervals were alulated t explre the relatinships f histry f dempressin illness, urrene f reurring, nn-disabling dempressin illness, evidene f jint damage, and evidene f spinal injury with mmunity, age f the diver, and duratin f diving f urrent divers. Assiatins between reurring nn-disabling dempressin illness and urrent diving praties and demgraphy were als explred using multivariate lgisti regressin.
7 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND RSULTS Interviews were nduted with 9 heads f villages, 342 ative divers, 26 disabled divers, and the families r lleagues f 29 males wh had died ver the past 5 years. The distributin f divers by age is presented in Figure (/) a; <1) X I 1 6 z 4 2 < Age Figure 1. Age distributin f urrently ative divers surveyed Diving-Related Mrtality The results f the survey f deeased divers indiated that there had been 29 deaths f males ver the age f 11 within the last 5 years amng the whle Urak Lawi ppulatin and that f these 29 deaths, 13 had dived using a mpressr (Table 1). Based n the estimated ppulatin f apprximately 4 divers at any ne time, the mrtality rate fr the ppulatin f divers was therefre 13/4 fr the 5-year perid. Six f the deaths were diretly attributable t diving leading t an upatinal death rate f 6 deaths per 4 divers ver 5 years r 1.2 deaths per year, equivalent t 3 deaths per 1, persn-years.
8 154 D. GLD T AL t D a. L " ~. a < < 5 <D 6 S f Q z z z in l NJ T /5 /5 <D ^ Z Z g Z ) T M T ) U ' Z a k_ 3 1 i n r <D D L D ) a a) < </ Q. W <d : * 5.a S. w Q..J. -Q 3 L - 1 2? _Q j/}^ ) =3 Q- _ T3 ) J 3 n= ) 1 6 g! D "D I! ««_ </) * 2 2 ) ( LL L Q_ " L sz ) -» 8 ~ "B < L «) I 1 S I aj 13 a? < a Z5.y Q * D r ^ «g < T3 TD _ - J "( i_ V Q) ) P 3 Q < ^ i^) ^) 5: a5 ) L < </. (S Q LU m < Q) ) ) < l l a F a) 3 a: z l T -vjd m ir) r^\j'tfin-«-\j\ji\j T - M ^ i n D S t- D m
9 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 155 L Q a a <n 5 <D 1 ^ 1 s t LU w L L L L L L M L L L i - M T - 5 m b L b l d b b jd g. l3 r LU Tz /) ) *tz ZJ /).Q *tz TJ ) **r <d t < ^ L- -Q ^ ~ -Q /) a -Q a) / -Q TD»_ T3 Q 1» I ~a JD X) ^ ) JD jq JD TABL 2. Disability Amng the Diving Ppulatin (1996, n = 26) r il < (.=L U) < l l P H *- 3 Z -Q -Q ZJ =5 _ Tz a) ZJ JZ TZ " =3 Q. 8 2 Z3 % := 3z - a M a L ^r \l _,\H j z Q) _J L \J» 'tf i 3 <J) ' m sz.2 Tz a) & _ J Jz w T - n Q 3 S _ N N L D -Q n JD l i! g a - 13 & M J, L ' _. t z _ D _ ~ ^ \J VJ ) "S S t : Z3 -»_ N - N " f " 5 d) L T T - T i T 1 T L
10 156 D. GLD T AL. stim ated Prfile Referene Year f Age at Parts f Im mediate f Last D ive Number Age Injury Injury nset f D iver-reprted Prblem Bdy Affeted ause (T im e/d epth)* 3 L \J.Q _ ~ -Q 13 _ 3 * 13 L % l 3 ID 3 in \j ID NJ " 3 X 3 u N.N Q \J ^5 i Z z ' 3 3 b *tz 13 3 id 3 \J \J Q Q. <I ) t - M In NJ D " -Q _3 3 t= 3 L - ~ T -Q 3 - JZ ~ 2 3 _ l LU *- ^ L T T - \J L n 3 *t= D _Q " 3 \J ID \J N T T y T T~ T L X \J 3 =3 -»_ -Q i s <13 - _ /T * 3 TZ 13 /). 13 a5 JD 3 Z X) "D 3 - NJ ID NJ ID ' ID M JD 5 ( Q. -Q _d sz _% L S 5 3 ^ ( 3-3 x: l "U D
11 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND Diving-Related Disabling Mrbidity Twenty-six divers wh had stpped diving were identified in the villages vered by the prjet. f the 26, 1 had stpped diving due t a hange in jbs, ne was fund t be still diving, and 2 indiated that they had never had a prblem while diving (Table 2). f the 22 remaining divers, the average age at time f injury was 34.5 years and the range was frm 23 t 53 years. Fllwing the injury, 13/19 (68.4%) had immediately eased diving. The reprted ause f the injury was related t the diving prfile suh as diving t deep, 26.3% (5/19); surfaing t fast, 36.8% (7/19); equipment failure, 1.5% (2/19); insuffiient air, 5.3% (1/19); nt knwn, 1.5% (2/19); and n ause 1.5% (2/19). The divers reprted that they had been healthy prir t the disabling injury. When asked abut persnal health prblems they had been infrmed abut by a health are wrker r a dtr prir t the event, 89.5% (17/19) reprted nne; 1/19 (5.3%) reprted irulatry prblems; and 5.3% (1/19) reprted eye prblems. Thirty perent (6/2) reprted taking mediatin befre the event, whereas 7% (14/2) denied ding s. It is widely knwn that the administratin f first aid suh as 1% xygen an redue the ptential fr serius injury. Immediate first aid was prvided n the bat fr 57.9% (11/19) f the divers. First aid prvided (as listed by the divers) inluded massage, 47.4% (9/19); a ht-water bttle, 5.3% (1/19); and painkillers 5.3% (1/19). Twenty-six pint three perent (5/19) f the divers reprted having reeived in-water rempressin as a treatment fr dempressin illness. Depth f rempressin was reprted t be 1 m and reprted times ranged frm 6 (2/3) t 12 min (1/3). Amng these diving-related disabling events, 11 were knwn t have urred within the previus 5 years. Again basing a alulatin n a ttal f apprximately 4 divers at any time, the apprximate rate f diving-related nn-fatal disabling events was 55 events per 1, persn-years, r abut twie the estimated diving-related mrtality rate Diving-Related Mrbidity Amng Ative Divers Regarding seleted manifestatins f dempressin sikness, 79.8% (265/332) ften reprted experiening jint pain, 76.2% (179/235) tingling, 67.2% (221/239) lss f sensatin, and 7.% (22/316) inability t mve.
12 158 D. GLD T AL. Thirty-six perent (121/336) f the divers reprted having experiened dempressin illness (Table 3), generally understd by the divers t refer t paralysis, unnsiusness, r ther serius signs and symptms. Using univariate analysis, mmunity f residene as well as age and years f diving were assiated with the reprted histry f dempressin illness. Divers living in Phuket Prvine (with the exeptin f Sapam mmunity) were mre likely t reprt a histry f dempressin illness (Table 3). Prbabilities f having a histry f dempressin illness als inreased with age (P-trend =.4) and years f diving experiene (P-trend =.4). TABL 3. Reprted Histry f Dempressin lllness(di) Reprted Histry f DI rude dds 95% nfidene Variable Level Number Prprtin Perentage Rati Interval D e m g r a p h i s Age grup / / / / / I mmunity Rawai 98 47/ Kh Siray 83 33/ Sapam 18 4/ Kh Lanta 49 13/ Kh Li Peh 65 19/ Kh Buln 18 1/ X TD i e n e Years diving / / / / Hwever, when reurring nn-disabling dempressin illness was assessed based n speifi reprted manifestatins, almst all urrent divers (325/332) were lassified as urrently experiening suspeted (39.5%) r prbable (58.4%) dempressin illness (Table 4). Demgraphi, experiene, and pratie fatrs independently assiated with experiening prbable reurring
13 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 159 TABL 4. Reurring, Nn-Disabling Dempressin Illness Amng urrently Ative Divers SI.2 S J Q. ) l) _ *= 8 S in n S -</. 2 ^ w r vy ) ja.2 3 /) SZ l 3 Q i n M n n T T r ^ n n n n n n n n i n i i i h - N I in i n» tj- 'r~ t~ \i NJ f r - r - ^ 5 ^ d * * f ''- \J n n M T i? 1 i 1 i in i n w ^ r^ t- -r^ T n»- i n i n i n i n i n i n M i n i n m i n ) s Q T - T f (D T - m s i n i n ^ m i n T~ T- 5 n 1 ' i n T i n M M i n T i n i n 5 y 1 5 T M i n M M i n M M n n n n m t- m I I I I I r - m ^ in 5i /) 3 r- <5 * D Q si 3 3 i_ 3 X LU n i n n n i n n i n 3 -r - ^ i n n ^ n n i n in n 3 Q / / / /
14 16 D. GLD T AL. - I S I I h* N N ))) L Is- 3 3 r^- 3 3 ^ h-1 Q 3 X I U L 2 15 ^ 7 'T n tj- 3 ^ ^ I I 3 M I I h - I L M I Is L X T3 L g - w 2 TJ w 6 3 N l t r L ) L _ X ) 3 -Q is J Q_ t T \J L h - L t ^ N ) ^ L l n NJ t - m NJ ) t- h - 3 NJ L L N m L 1 L L T - L 3 L Is- h - 3 L L M 3 T t T t T- L L M T - 3 h - L M L V s 3 /3 * n 3 j L i L NJ T L ^ r - <t ) N M M Is- d ^ r L </ =3 IS Q. l ) W ) NJ T - NJ NJ ) ^ l m ^ 3 h - 3 T t M 3 L Is- M 3 L Is- L M L M 3 M L D /3 n 3 TABL 4. (ntinued) n n t- I l I t- NJ - ) </) 3» - < T - 1 J, % 3 ~?) T3 3 3 < V) XL *- g «1 ) b sz 2 X n TD U) - 3 / L Q (/) J L / d 3 T 6 1 ^ '8-1 Q- </ ) I < "
15 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 161 a ) 1 1 L </ T3 T3.2 Q) D 3u. I I I L d t T l \i -»- I t-' T T 1 T" T" N ) r- l ) l l \i ^ \i T- \J \J d ^ M L T T M t- M N ) M t L M- ^ L t L L t «- ^ T- T- N w s.z l 3 i Q L \J XT t ^ ^ L \J L T- ^ L L M L M M ^ T -rt 1- M T- t- ^ i_ X LU ^ M L r - TABL 5. Indiatins f Jint Damage _ n u (U L M ^ L i - ^ L M Tt L N ^ M I- M i T- M ^ L T - T - t- ^ T- T- ^ M M /D 1 3 r- w ^ \J U ) T - ^ M ^ M ^ M L t - L *- M i i i i i - M T3 3
16 162 D. GLD T AL. TABL 6. Indiatins f Spinal Injury </ X 3 <D </ D X ) T5 r k_ <i) ju m ) (7) <1 _ ~ T (U 1 a m TJ 75 r X- ) Ta in ) ;g ^ a l ) </ ~.2 *-» m r D D a ) r <D i (1) Q. X- L n «5< h- 9 l d 1- M I I I M d d t- T- T \j \j t ^ N M M ^ d in m d ^ i n M ^ in M M ^ NT m in I n ^ w ^ d ^ in M ^ ) J) M t - M ^ D i t m in n < N m in I I T- I J^t»- N \j i n»- ^ T - \i N \i r - ( D T- ^ T- ^ ^ -r- ^ T- M t- ^ M M '» ' - 1- i- ^ r ^ ^ M ^ Q r D (/) 3 5 * * ) l) L X LU U Years -9 1/24 3/24 1/24 1/24 /24 1/24 5/ diving /49 5/49 1/49 3/49 2/49 3/49 1/ /18 3/18 2/18 1/18 /18 1/18 6/ /4 1/4 /4 /4 /4 /4 1/
17 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 163 dempressin illness were explred using multivariate lgisti regressin. Hwever, evidene f assiatin was fund nly fr mmunity f residene (p likelihd rati test =.11), with urrent divers in Kh Siray and Kh Lanta signifiantly mre likely t suffer frm reurring nn-disabling dempressin illness than thse in Kh Buln and Sapam. Althugh nt statistially signifiant, amng the sample f urrent divers thse wh were lder, had dived fr lnger, r reprted high risk dive prfiles had higher perentages f prbable reurring nn-disabling dempressin illness (Table 4). All f the 98 divers given a physial examinatin were ative divers. Jint damage is shwn in Table 5. Pain in ne r mre jints at rest r with manipulatin was present in 38.8% (38/98) f the divers examined. repitus in ne r mre jint was fund in 18.4% (18/98) and restrited mvement in ne r mre jint amng 5.1% (5/98). In a univariate analysis, the prbability f having jint damage inreased with years f diving (p-trend =.15) but there was little evidene fr an assiatin with age (p-trend =.152). Differenes amng the mmunities f residene were nt statistially signifiant, prbably due t the small numbers available. Hwever, within the sample examined, the perentages f divers with jint damage were higher amng the mmunities f Sapam and Kh Lanta than amng thse f Rawai and Kh Siray. Indiatins f spinal injury are shwn in Table 6. lnus was present in 15.5% (15/97), mst f whm (12/15) had bilateral lnus. Raised musle tne in the lwer limbs was fund in 1.3% (1/97) f divers, half f them (5/1) bilateral. Reflexes were graded n a sale t Heightened reflexes (+ + +) were fund in the knee f 6.2% (6/97) divers, amng whm 4 were bilateral, and in the ankle f 4.1 % (4/97) f divers, amng whm 3 were bilateral. Ten pint seven perent (9/84) f divers shwed a Babinski sign, 5 f them bilateral. In univariate analysis there was little evidene f a trend f inreased prbability f having spinal injury with inreasing age (P-trend =.89), and n evidene f an assiatin with years f diving (P-trend =.433). 4. DISUSSIN This study has revealed high estimated mrtality rates amng the Urak Lawi divers as well as high prevalene f disabling and nn-disabling mrbidity as a result f diving.
18 164 D. GLD T AL. The Internatinal Labur ffie uses deaths per 1, wrkers per year t assess the rate f upatinal fatalities. In Thailand, ne f the mre visible dangerus upatins is building-nstrutin wrk. In 1995, there were 154 deaths f nstrutin wrkers ut f the 248,569 that were vered by the W rkman s mpensatin Fund (R. Thngmuang, persnal mmuniatin, February 22, 1999) r 7 deaths per 1, wrkers. Frm this study, it an be estimated that the rate f upatinal fatalities amng the Urak Lawi is 3 deaths per 1, wrkers per year. Within this relatively yung ppulatin, there is a nsiderable diving-related mrtality and disabling mrbidity. Based n the estimate f a ttal f apprximately 4 ative divers, the prevalene f diving-related disabling mrbidity amng divers and ex-divers is apprximately 5.2% (22/422). ven amng the urrently ative divers, almst 6% are prbably suffering frm reurring nn-disabling dempressin illness, and in a subset f 98 divers the prevalene f spinal injury was 22.7% (22/97) and f jint damage 3.6% (3/98). Pssible explanatins fr the apparent assiatin f these prevalent nditins with age r years f expsure inlude (a) inreased suseptibility with age, (b) umulative effet f expsure, () inreased prbability f an injurius event with inreased time at risk, and (d) a seular redutin in the abslute risk. With the limited data available in this study, it is nt pssible t distinguish these ptential explanatins fr assiatin. Althugh the sientifi literature ntains ertain infrmatin abut hspital r dempressin hamber-based diving-related mrtality and mrbidity fr surfae (air) supplied indigenus divers, there is limited infrmatin available n a ppulatin basis. nly dmnds (1996) suggests, after a review f divers lg bks, a diving-related mrbidity, hwever the diving praties f the Australian pearl divers addressed by dmnds are nsiderably different frm the divers under study. There are several desriptins f diving praties and dempressin sikness in grups f fisherman divers in Australia (Ganter, 1994; Wng, 1996), the ntinental USA (Butler, 1995), Hawaii (Kizer, 1982; Wade, Hayashi, ashman, & Bekman, 1978), Japan (Kawashima et al., 1995; Mhri et al., 1995), Mexi (Jnes, Ramirez, & Dty, 1993), the island f Pesadres (Lee et al., 1994), the Philippines (Ball, 1993), the Republi f Krea (Park & Hng, 1991), Singapre (Hw & Lng, 1995), and the Territry f Hng Kng (Lam, Yau, & Kelley, 1985). Differenes in the prevalene f reurring nn-disabling mrbidity amng the mmunities were nt nfunded by any f the diving pratie
19 INDIGNUS DIVING RLATD MRTALITY AND MRBIDITY: THAILAND 165 variables inluded in the multivariate analysis. It is pssible, hwever, that ther features f the diving pratie, nt rerded in this study, differed amng the mmunities. A mpliatin in examining these fatrs is that the Urak Lawi may migrate, frm time t time, frm ne village t anther. Relatinships between diving praties and mrbidity was explred nly fr the mpsite variable f suffering frm dempressin illness n a regular basis, as the diretin f ausality in any assiatin between urrent diving praties and the ther mrbidity variables (histry f dempressin illness, spinal injury, and jint damage) uld nt be asertained. An attempt was made t aess every member f the three grups f the ppulatin nerned. It is likely that the attempt was smewhat less suessful fr the ative diver grup than fr the ther tw grups. Nevertheless, based n the estimated ppulatin f the ttal f 4 ative divers, the reruitment rate was apprximately 85%. Arding t the heads f villages, the ttal number f ative divers had nt hanged substantially ver the previus 5 r mre years. ur estimates f diving-related mrtality and diving-related disabling event rates are unlikely t be in serius errr as a result f hanges in the size f the ppulatin at risk ver time. Prevalene estimates f reprted experiene f dempressin illness and f reurring, nn-disabling dempressin illness amng urrently ative divers, hwever, may be smewhat less infrmative bth as a result f the healthy wrker effet (Fx & llier, 1976), whereby thse members f the diving mmunity mst severely affeted are gradually remved frm the ppulatin f urrently ative divers, and pssibly als wing t any bias in the grup f ative divers interviewed. Nevertheless, the Urak Lawi ppulatin in Thailand is relatively lsed, with migratin nfined almst entirely t hange f residene t ther Urak Lawi villages. Divers wh stpped diving beause f disability r death were therefre readily identified in this survey. Bias may have been mre serius, hwever, in the use f an availability sample f ative divers fr the physial examinatin. Divers with rather greater mrbidity may have been mre available and thereby be ver-represented in the sample. If this is the ase, the prevalene f jint damage and spinal injury amng urrently ative divers may have been smewhat verestimated. It is already reprted that diving praties f the Urak Lawi far exeed what wuld be nsidered safe in aviding dempressin illness by aepted standards fr ivilian and military diving. In view f the high levels f mrtality and mrbidity revealed in this study a primary apprah t reduing mrtality and mrbidity appears t be t mdify diving
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