Background: The Hospital Ferreira Machado, utilized, in part, as a clinical training center for graduate students from the Faculdade de Medicina de Campos, admitted 65 tuberculosis (TB) patients in 2001.
Objective: To estimate the prevalence of positive tuberculin skin tests (TST) among medical students during distinct periods of their training and to identify and analyze correlated factors. To compare positivity rates, taking into account the booster effect, and estimate incidence of positive TST by class year.
Methods: A cross- sectional study was conducted among 500 students registered in the first semester of 2002. Using a structured and validated questionnaire, data regarding demographics, BCG vaccination and potential exposure to TB patien ts were obtain ed. A profession al licen sed by the Health Departmen t admin istered the TSTs, an d the two- step Mantoux method (PPD Rt23) was used.
Results: Of the 500 eligible subjects, 316 (63.2%) were excluded. Analysis showed increasing two- step TST positivity rates correspon din g to exten t of clin ical experien ce (4%, 6.4% an d 13.1%) an d a ten den cy toward correlation with profession al level. The highest percen t age of posit ive TSTs was fou n d du rin g t he period of clin ical t rain in g, which corresponded to the time of greatest exposure to patients (1000 hours).
Conclusions: a) the TST positivity rate was high (7.9%) among students; b) TST was correlated with in- hospital training stage; c) evaluation of the booster effect lead us to highly recommended boosters in order to reduce the number of false-negative TST results.
Key words: Tuberculin. Tuberculin test. Tuberculosis. Students/Medical. Cross- sectional studies.
St u d y carried o u t b y t h e Red e Brasileira d e Pesq u isa em TB (Red e- TB, Brazilian Tu b ercu lo sis Research Net wo rk) at t h e Cam p o s Sch o o l o f Med icin e, Rio d e J a n eiro , RJ
Co rresp o n d en ce t o : Ru a Co n selh eiro Ot a via n o , 8 4 – sa la 9 01 – CEP 2 8 010 - 1 4 0 – Ca m p o s – Rio d e J a n eiro – RJ E- m a il: lcp a re n t @ u o l.co m .b r
Sp o n so r: Re d e Bra sile ira d e Pe sq u isa e m TB (Re d e - TB, Bra z ilia n Tu b e rcu lo sis Re se a rch Ne t wo rk)/ Gra n t n o . 6 2 .0 0 5 5 / 01 - 4 - PACDT- Mile n io .
Jornal Brasileiro de Pneumologia 3 0 (4 ) - Jul/ Ago de 2 0 0 4
Abbreviations used in this paper: AIDS– Acq u ire d im m u n o d e ficie n cy syn d ro m e BCG – Ba cillu s Ca lm et t e- Gu érin
FMC – Fa cu ld a d e d e Med icin a d e Ca m p o s (Ca m p o s Sch o o l o f Me d icin e )
HFM – Ho s p it a l Fe r r e ir a M a c h a d o (Fe r r e ir a M a c h a d o Ho sp it a l)
Mt b – Myco b a ct eriu m t u b ercu lo sis
PPD – Pu rified p ro t ein d eriva t ive OR – Od d s Ra t io
TB – Tu b ercu lo sis TST – Tu b ercu lin Skin Test
URFJ – Un ive rsid a d e Fe d e ra l d o Rio d e J a n e iro (Rio d e J a n eiro Fed era l Un iversit y)
INTRODUCTION
In t h eo ry, t h e m ed ical st u d en t s at t en d in g t h e Facu ld ad e d e Med icin a d e Cam p o s (FMC, Cam p o s Sch o o l o f Med icin e) co m e fro m fam ilies wh o se in co m es a re well a b o ve t h e n a t io n a l a vera g e. Th erefo re, it is assu m ed t h at t h e p revalen ce o f lat en t t u bercu losis (TB) or act ive TB wou ld be lower a m o n g t h e s e s t u d e n t s t h a n in t h e g e n e r a l p o p u l a t i o n(1 ). Th e r i s k o f M y c o b a c t e r i u m
t u b ercu lo sis (Mt b ) in fect io n in t h e h o sp it a l in wh ich t h ese st u d en t s a re t ra in ed is u n kn o wn . Im p le m e n t a t io n o f m e a s u r e s t o c o n t r o l TB in fect io n am o n g m ed ical st u d en t s is co n sid ered u n n e c e ssa ry b y t h o se w h o f o rm u la t e p u b lic p o licies(2 ). Ho wever, a st u d y was co n d u ct ed at t h e
Un iversid ad e Fed eral d o Rio d e J an eiro (UFRJ , Rio d e J an eiro Fed eral Un iversit y), wh ere 9 3 .5 % o f m e d ica l st u d e n t s co m e f ro m f a m ilie s w h o se m o n t h ly in co m es are, o n averag e, t en t im es t h e m in im u m wag e(3 ). Th e au t h o rs sh o wed t h at t h e
prevalen ce of lat en t TB am on g st u den t s in clin ical t rain in g was seven t imes higher t han t hat est imat ed fo r t h e g en eral p o p u lat io n .
Me d ic a l st u d e n t s a t t h e FMC re c e ive d t h e ir clin ica l t ra in in g a t t h e Ho sp it a l Ferreira Ma ch a d o (HFM, Ferreira Ma ch a d o Ho sp it a l). An n u a lly, t h is h o sp it a l a d m it s m o re t h a n 6 0 p a t ien t s d ia g n o sed wit h pu lm on ary TB in accordan ce wit h est ablished p ro t o co ls a n d crit eria . Th e HFM ca n b e cla ssified a s a m o d e r a t e - r is k e n vir o n m e n t r e g a r d in g o u t b rea ks o f n o so co m ia l TB(5 ) a n d is a referen ce
cen t er fo r a cq u ired im m u n o d eficien cy syn d ro m e (AIDS) p a t i e n t s f r o m t h e n o r t h e r n a n d n o rt h ea st ern reg io n s, a s well a s fro m t h e Reg iã o d o s La g o s (La kes Reg io n ), o f t h e st a t e o f Rio d e J a n eiro .
At t h e FMC, m ed ical st u d en t s in t h e b asic p h ase (BP) o f t h eir t rain in g d o n o t p art icip at e in p at ien t exam in at io n s o r t reat m en t . Co n t act wit h p at ien t s in cre a se s p ro g re ssive ly fro m t h e in t e rm e d ia t e clin ical p h ase (ICP) o n ward in t o t h e p ro fessio n al-p h ase (PP). Th e in cid en ce o f al-p o sit ive t u b ercu lin skin t est s (TSTs) amon g medical st u den t s who may h a ve b e e n in fe ct e d wit h Mt b h a s n e ve r b e e n assessed . Th erefo re, a cro ss- sect io n al st u d y, u sin g TSTs, wa s co n d u ct ed in o rd er t o est im a t e t h e p re va le n ce o f Mt b in f e ct io n a m o n g m e d ica l st u d en t s d u rin g d ist in ct p erio d s o f t h eir t rain in g . Co m p ariso n s were m ad e am o n g t h e BP, ICP an d PP g ro u p s o f st u d en t s.
METHOD
In 2 0 0 2 , a cro ss- sect io n al st u d y was carried o u t in o rd er t o est im at e t h e p revalen ce o f p o sit ive TSTs am o n g PB, PCI an d PP m ed ical st u d en t s at t h e FMC, a s we ll a s t o id e n t ify a n d a n a lyz e correlat ed fact ors. All st u den t s en rolled in t hat year were elig ib le fo r t h e st u d y. We fo u n d n o st u d en t s eit h er wit h act ive TB, wit h a clin ical h ist o ry o f TB or u n dergoin g im m u n osu ppressive t hera py, an y of wh ich wo u ld ju st ify exclu sio n fro m t h e p ro g ram . Th e st u d y was ap p ro ved b y t h e Research Et h ics Co m m it t ee o f t h e UFRJ Ho sp it a l Un iversit á rio Clem en t in o Frag a Filh o (Clem en t in o Frag a Filh o Un iversit y Ho sp it al) an d rat ified b y t h e Research Et h ics Co m m it t ee o f t h e FMC.
Approximat ely 500 st u den t s per year begin t heir m ed ical t rain in g at t h e FMC. Th e st u d y su b ject s were d ivid ed in t o t h ree levels b y ext en t o f clin ical experien ce. As part of t heir regu lar schedu les, first -an d seco n d - year (BP) st u d en t s h ave co n t act wit h p at ien t s fo r less t h an 10 0 h o u rs p er year, wh ereas t hird- an d fou rt h- year (ICP) st u den t s have bet ween 1 0 0 an d 1 0 0 0 h o u rs o f co n t act , an d fift h - an d sixt h - yea r (PP) st u d en t s h a ve m o re t h a n 1 0 0 0 h o u rs.
All part icipat in g su bject s gave writ t en in formed con sen t an d complet ed a validat ed qu est ion n aire(3),
TABLE 1 Frag a (Pro fesso r Hélio Frag a Nat io n al Referen ce Cen t er for TB) an d is equ ivalen t t o t he st an dard 5-TU PPD dose. A profession al licen sed by t he Healt h Dep art m en t ad m in ist ered t h e TSTs. In d u rat io n at t h e PPD in ject io n sit e was m easu red b y p alp at io n at 4 8 - 7 2 h o u rs aft er in ject io n .
St u d e n t s wh o h a d re a ct io n s o f < 1 0 m m in du rat ion were re- t est ed (at least ) on e t o (at most ) t h ree weeks la t er. Th o se wh o h a d rea ct io n s o f 1 0 m m in d u r a t io n a f t e r t h e f ir s t TST w e r e co n sid ered t o h ave a react ive (p o sit ive) TST an d were n o t re- t est ed . Po sit ive TST was d efin ed as a react io n o f 1 0 m m in d u rat io n t o t h e first TST o r a p o sit ive b o o st e r e f f e ct (re a ct io n o f 1 0 m m in du rat ion ) t o t he secon d TST(7). The boost er effect
was co n sid ered p o sit ive wh en in d u rat io n aft er t h e
st u den t s who presen t ed expect orat ion ). All of t hese st u d en t s were ad vised t o seek m ed ical assist an ce if t h ey exp erien ced resp irat o ry sym p t o m s d u rin g t h e st u d y.
Th ere were a t lea st 4 8 0 g ra d u a t e st u d en t s en ro lled at t h e FMC in 2 0 0 2 . Takin g in t o acco u n t an est im at ed 2 .6 3 % in cid en ce o f p o sit ive TST at t h e b e g in n in g o f t h e c o u rse a n d a 1 6 .1 8 % in cid e n ce a t t h e e n d o f t h e co u rse(3 ), a 9 5 %
co n fid en ce in t erval (9 5 % CI), st at ist ical p o wer o f 8 0 % an d a t wo - t ailed ± o f 0 .0 5 , t h e m in im u m n u m b e r o f s u b je c t s n e e d e d t o c o n d u c t a n in vest igat ion wou ld be 172. A con ven ien ce sam ple t h at su rp asses t h e m in im u m n u m b er was u sed .
Co rre la t io n s b e t we e n ca t e g o rica l va ria b le s a n d t h e o u t co m e were d et erm in ed u sin g t h e ch
i-Caracteristic Medical Students
Number/ Total (%)
Su bmit t ed t o at least 1 complet e TST process 345/500 (69.0)
Su bmit t ed t o 2 complet e TST processes 311/500 (62.2)
Included 316/500 (63.2)
Mean age (years ± SD) 21.7 ± 2.3
Female 161/316 (50.9)
Male 155/316 (49.1)
Professed previou s BCG vaccin at ion 269/316 (85.1)
Presen ce of BCG vaccin at ion scar 281/316 (88.9)
Brazil Crit erion socioecon omic class: Class A – 104/ 316 (32.9) Class B – 103/ 316 (35.7) Class C – 18/ 316 (5.6)
Con t act wit h TB in t he home 13/316 (4.1)
In t ern ship in TB t reat men t 8/316 (2.5)
In t ern ship in a hospit al u n affiliat ed wit h t he FMC 166/316 (52.5)
Basic phase of t rain in g 100/316 (31.6)
In t ermediat e clin ical phase of t rain in g 109/316 (34.5)
Profession al phase of t rain in g 107/316 (33.9)
TST: t u b ercu lin skin t est ; SD: st a n d a rd d evia t io n ; BCG: Ba cillu s Ca lm et t e- Gu érin ; ; TB: t u b ercu lo sis; FMC: Fa cu ld a d e d e Med icin a d e Ca m p o s (Ca m p o s Sch o o l o f Med icin e)
Jornal Brasileiro de Pneumologia 3 0 (4 ) - Jul/ Ago de 2 0 0 4
sq u a re t est o r, wh en in d ica t ed , Fish er’s exa ct t est . Co rre la t io n s b e t we e n co n t in u o u s va ria b le s a n d t h e o u t c o m e w e r e d e t e r m i n e d u s i n g t h e St u d e n t ’s t- t e st o r, wh e n in d ica t e d , Kru ska l-Wa llis t e st . Th e le ve l o f st a t ist ica l sig n ifica n ce wa s set a t 5 % . In o rd er t o co m p a re t h e in cid en ce a m o n g g ro u p s, t h e ra t io o f t h e p ro p o rt io n s (o d d s ra t io ) wa s d e scrib e d u sin g a 9 5 % co n fid e n ce in t e rva l. Du rin g t h e e le ct ro n ic p ro ce ssin g a n d a n a lysis, d a t a co llect ed fro m t h e q u est io n n a ires were in p u t in t o t h e J a n u a ry 2 0 01 EPI INFO 6 .0 4 st a t ist ica l a n a lysis a p p lica t io n(1 0 ), wh ich wa s u sed
t o ca rry o u t u n iva ria t e a n d b iva ria t e a n a lysis o f d ich o t o m o u s a n d co n t in u o u s va ria b les. In o rd er t o id e n t ify in d e p e n d e n t fa ct o rs co rre la t e d wit h p o sit ive TST in t h e st u d y su b je ct s, m u lt iva ria t e an alysis wit h lo g ist ical reg ressio n was carried o u t . Th e STATA 7 . 0 p r o g r a m w a s u s e d f o r t h e m u lt iva ria t e a n a lysis, wh ich in clu d ed a ll va ria b les a t t a in in g p va lu e s d • 0 . 0 5 in t h e b iva r ia t e a n a lysis.
RESULTS
Of t h e 5 0 0 st u d en t s en ro lled at t h e FMC in 2 0 0 2 , 2 5 9 (51 .8 %) were m ales an d 2 5 8 (51 .6 %) were ab o ve t h e ag e o f 2 1 (Tab le 1 ). Every effo rt was m ad e t o in vo lve all 5 0 0 . We visit ed lo cat io n s w h e re cla sse s o r p ra ct ica l a ct ivit ie s w e re in p ro g ress, g ave lect u res o n o u r st u d y, an d in vit ed volu n t ary part icipat ion .
A t o t a l o f 4 0 0 (8 0 % ) o f t h e st u d e n t s fille d o u t t h e q u est io n n a ire a n d g a ve writ t en in fo rm ed co n se n t . Th e first TST wa s a d m in ist e re d t o 3 5 0 st u d e n t s (7 0 % ), a n a lyz e d in 3 4 5 (6 9 % ), a n d fo u n d t o b e p o sit ive in 5 (2 fro m t h e ICP a n d 3 fro m t h e PP), fo r a p re va le n ce o f 1 .4 % . A t o t a l o f 3 2 0 st u d en t s (6 4 % ) u n d erwen t a seco n d TST, wh ich wa s a n a lyz e d in 311 (6 2 .2 % ) a n d fo u n d t o b e p o sit ive in 2 0 (6 .4 % o f t h e 311 ). Th e in cid e n ce o f p o sit ive b o o st e r e ffe ct wa s 5 .8 % (1 8 / 311 ). Th e ra t e o f p o sit ivit y fo r t h e first a n d s e c o n d TSTs c o m b in e d w a s 7 . 9 % (2 5 / 3 1 6 ) (Ta b le s 1 a n d 2 ).
TABLE 2
Results of bivariate analysis of extra- curricular factors correlated w ith positive TST among medical students; Campos (RJ), 2 0 0 2
Ext ra - cu rricu la r fa ct o r +TST –TST OR 9 5 % CI p
n (%) n (%)
25 (7.9) 2 91 (92.1) (95%CI) Ag e
> 2 1 18 (11.0) 1 4 6 (95.4)
≤ 2 1 7 (4.6) 1 4 5 (89.0) 2.57 (0 .9 8 – 7 .0 2 ) 0.03** Gen d er
Ma le 1 0 (6.5) 1 4 5 (93.5)
Fem ale 1 5 (9.3) 1 4 6 (90.7) 0.67 (0 .2 7 – 1 .6 5 ) 0 .3 5 ** Presen ce o f BCG sca r 2 5 (8.9) 2 5 6 (90.1)
Ab sen ce o f BCG sca r 0 (0.0) 4 0 (100.0) N/ A N/ A 0 .0 4 * So cio eco n o m ic St at u s
Cla ss A 12 (6.5) 1 7 2 (93.5) 1 -
-Cla ss B 10 (8.8) 1 0 3 (91.2) 1.39 (0 .5 8 - 3 .3 3 ) 0.46 Cla ss C 3 (15.0) 1 6 (85.0) 2.69 (0 .6 9 – 1 0 .5 2 ) 0.16 Co n t a ct wit h TB in t h e h o m e±
Yes 0 (0.0) 1 2 (100.0)
No 25 (8.7) 2 6 4 (91.3) 0.00 (0 .0 0 – 4 .0 7 ) 0.34* Tim e sin ce BCG va ccin a t io nβ
≤ 2 yea rs 3 (30.0) 7 (70.0)
> 2 yea rs 1 0 (7.8) 1 2 0 (92.2) 5.14 (0 .8 9 – 2 7 .7 3 ) 0.05* Tim e sin ce BCG va ccin a t io nβ
< 4 yea rs 4 (26.7) 11 (73.3)
> 4 yea rs 9 (7.2) 11 6 (92.8) 4.69 (1 .01 – 2 0 .8 4 ) 0.03* TST: tuberculin skin test; BCG: Bacillus Calmette-Guérin; TB: tuberculosis; OR: odds ratio; 95% CI: 95% confidence interval
3 4 .5 % (10 9 / 31 6 ) were ICP st u d en t s, an d 3 3 .9 % (1 0 7 / 31 6 ) w e re P P s t u d e n t s (Ta b le 1 ). Th e m in im u m len g t h o f at t en d an ce was 1 m o n t h an d t h e m axim u m was 8 4 m o n t h s (m ean , 3 6 m o n t h s). Am o n g t h e 1 8 4 st u d en t s wh o were n o t in clu d ed in t h e st u d y, 3 6 .4 % (6 7 / 1 8 4 ) were BP st u d en t s, 29.3% (54/ 184) were ICP st u den t s, an d 34.3% (63/ 1 8 4 ) were PP st u d en t s.
Th e rat e o f p o sit ivit y fo r t h e first an d seco n d TSTs co m b in ed was 7 .9 % (2 5 / 31 6 ), rep resen t in g 4 % (4 / 1 0 0 ) in t h e PB, 6 .4 % (7 / 1 0 9 ) in t h e ICP an d 1 3 .1 % (1 4 / 9 3 ) in t h e PP (Tab le 3 ).
No sig n ifican t co rrelat io n was fo u n d b et ween p o sit ive TST an d so cio eco n o m ic st at u s, co n t act wit h a pu lm on ary TB pat ien t in t he fam ily, gen der,
Th e b o o st er effect wa s n o t co rrela t ed wit h g en d er (p = 0.37), age (p = 0.16), BCG vaccin at ion (p = 0 .10 ) o r class year (p = 0 .11 ).
In t h e in it ia l m u lt iva ria t e a n a lysis, va ria b les fou n d t o be st at ist ically sign ifican t in t he bivariat e an alyses were evalu at ed , b ased o n d at a co llect ed fro m o n ly 1 4 0 st u d en t s (t h o se wh o p ro vid ed su ch d a t a ). Ho wever, a ft er verifyin g t h e p resen ce o f co lin earit y, o n ly t h ree variab les were t aken in t o acco u n t : in t ern sh ip in h o sp it als u n affiliat ed wit h t h e m ed ical sch o o l, t im e sin ce BCG vaccin at io n eq u al t o o r less t h an fo u r years, an d b ein g a PP st u d en t . Am o n g t h ese variab les, t im e sin ce BCG vaccin at io n eq u al t o o r less t h an fo u r years (p = 0 .0 5 ; 9 5 % CI = 0 .9 9 – 1 5 .9 9 ) an d b ein g a PP
TABLE 3
Results of bivariate analysis of curricular activities correlated w ith positive TST among medical students; Campos (RJ), 2 0 0 2
Curricular +TST – TST OR 9 5 % CI p
activity n (%) n (%)
25 (7.9) 291 (92.1) Cla ss yea r
BP 4 (4.0) 96 (96.0) 1
ICP 7 (6.4) 102 (93.6) 1.65 (0 .4 7 – 5 .0 8 ) 0.44 PP 14 (13.1) 93 (86.9) 3.61 (1 .1 5 – 11 .3 8 ) 0.03 Previou s in t ern ship
Yes 11 (9.6) 103 (90.4)
No 14 (6.9) 204 (93.1) 1.43 (0 .5 8 – 3 .51 ) 0.39** Trea t ed a TB p a t ien tα
Yes 12 (11.0) 97 (89.0)
No 11 (6.3) 164 (93.7) 1,84 (0 .7 3 – 4 .6 9 ) 0.15** Clin ica l t ra in in g
in a TB clin icβ
Yes 0 (0.0) 8 (100.0)
No 25 (8.2) 280 (91.8) 0.00 (0.00- 6.97) 0.50*
Clin ica l t ra in in g in a n o t h er h o sp it a lφ
Yes 16 (10.9) 131 (89.1)
Jornal Brasileiro de Pneumologia 3 0 (4 ) - Jul/ Ago de 2 0 0 4
st u d en t (p= 0 .0 6 ; 9 5 % CI = 0 .9 6 – 2 8 .0 7 ) sh o wed a t en d en cy t o wa rd sig n ifica n t co rrela t io n wit h p o sit ive TST (Tab le 4 ).
DISCUSSION
Cro ss- sect io n al st u d ies h ave a lim it ed cap acit y t o d et erm in e cau sal relat io n sh ip s. A lo n g it u d in al st u d y wo u ld b e m o re su it ab le fo r an alyzin g t h e risk o f in fect io n an d co rrelat ed fact o rs, an d t h e co n ve rsio n ra t e . Wit h in o u r m ilie u , Mu z y d e So u za(13) co n d u ct ed a st u d y t h at in vo lved b o t h
cro ss- sect io n a l a n d lo n g it u d in a l a n a lysis. Th e au t hor report ed t hat , in t he cross- sect ion al an alysis, t h e p reva len ce o f Mt b in fect io n a m o n g h ea lt h p ro fessio n als was 51 % an d , in t h e lo n g it u d in al an alysis, t h e rat e o f TST co n versio n was 8 .7 %. There is lit t le su ch dat a regardin g medical st u den t s in d evelo p in g co u n t ries. In a st u d y co n d u ct ed in Mexico , Mu ñ o z- Barret et al.(14) d escrib ed a 41 %
prevalen ce Mt b in fect ion amon g fift h- year medical st u d en t s an d a 1 4 % p revalen ce am o n g first - year st u d en t s. Based o n t h e resu lt s o f o u r st u d y, wh ich sh o w rat es o f TST p o sit ivit y in creasin g in p arallel wit h class year, we fo rm u lat ed t h e h yp o t h esis t h at TST co n versio n o ccu rs in t h e p erio d o f m o re freq u en t clin ical p ract ice, as h as b een p revio u sly rep o rt ed(3 ,11 ,1 2 ). In u n iversit y h o sp it als in t h e cit ies
o f Rio d e J an eiro an d Nit eró i (b o t h lo cat ed in t h e st a t e o f Rio d e J a n eiro ), Ferreira(11 ), Silva(3 ) an d
Co st a(1 2 ) co n d u ct e d st u d ie s in vo lvin g m e d ica l
st u den t s in t he same age bracket as t hose evalu at ed in t h e p resen t st u d y. Th e a u t h o rs rep o rt ed t h e p revalen ce o f Mt b in fect io n t o b e 2 0 .4 %, 9 .2 % a n d 3 .6 % , re sp e ct ive ly. Fe rre ira(11 ) a n d Silva(3 )
d em o n st rat ed a sig n ifican t d ifferen ce b et ween PP an d PB st u d en t s in TST p o sit ivit y rat es. Co st a(12)
d escrib ed a 7 .5 % rat e o f TST co n versio n am o n g in t ern s (sixt h - year PP st u d en t s).
Th ere wa s a h ig h p ro p o rt io n o f u n in fect ed st u d en t s in o u r sam p le (3 2 0 / 3 4 5 ), as well as in t h o se o f Ferreira (3 5 5 / 4 4 6 )(11 ) a n d Silva (41 3 /
4 5 5 )(3 ). Th is in d ic a t e s t h a t , a m o n g st u d e n t s
practicin g in u n iversity hospitals an d AIDS referen ce cen t ers in t h e st at e o f Rio d e J an eiro , t h ere are m a n y wh o h a ve n e ve r b e e n e xp o se d t o Mt b . Th erefo re, t h ese st u d en t s a re a t h ig h risk fo r in fect io n b y t h e TB b a cillu s if t h e ra t e o f TB t ra n sm issio n in c re a se s in t h e se in st it u t io n s, e sp e cia lly in t h o se w h ich h a ve n o t a d o p t e d ap p ro p riat e b io safet y m easu res(2 ).
Th e p revalen ce o b served in o u r st u d y is lo wer t h an t h at o b served by Ferreira(11 ) o r Silva(3 ). Th is is
du e in part t o t he fact t hat ou r sample is comprised o f yo u n g er st u d en t s an d t h at t h eir so cio eco n o m ic st at u s is higher t han t hat of t he gen eral popu lat ion . It is also n ecessary t o t ake in t o acco u n t t h e fact t hat ou r st u dy was con du ct ed in a cit y wit h a lower popu lat ion den sit y an d lower in ciden ce of TB t han t he cit ies where t he above- men t ion ed st u dies were co n d u ced . It is also n o t ab le t h at so m e b io safet y m easu res, su ch as t h e im p lem en t at io n o f n o rm s a n d p ro t o co ls fo r p reven t in g TB t ra n sm issio n a m o n g h ea lt h - ca re wo rkers(7 ), h ave b een u sed at
t h e st u d y sit e (HFM) sin ce 1 9 9 9 . Su ch m easu res may have con t ribu t ed t o redu cin g TB t ran smission . Th is st u d y sh o wed a clear co rrelat io n b et ween p o sit ive TST an d BCG vaccin at io n (Tab le 2 ), as report ed by ot her au t hors(14,15). Nevert heless, based
o n t h e p resen ce o f BCG vaccin at io n scar, t h ere is st ill a t en d en cy t o ward co rrelat io n b et ween b ein g a PP st u d en t an d p o sit ive TST.
The boost er effect was n ot correlat ed wit h BCG vaccin at ion an d fu rt her research is n eeded in order t o in vest ig at e t h e afo rem en t io n ed p h en o m en o n , esp ecially wit h in p o p u lat io n s wh o live in reg io n s where t here is a high prevalen ce of n on t u bercu lou s m ycobact eria.
Th is st u d y h as it s lim it at io n s. Even t h o u g h we exceed ed t h e n u m b er o f st u d en t s est im at ed in t h e in it ial sample calcu lat ion , t here was a select ion bias in t h e s t u d y d u e t o t h e f a c t t h a t s t u d e n t part icipat ion was opt ion al. Nevert heless, t here are n o m ech an ism s fo r m akin g st u d en t p art icip at io n in t his kin d of st u dy com pu lsory. It is possible t hat st u d en t s wh o kn ew t h at t h ey were TST react ive avo id ed p art icip at in g in t h e st u d y an d t h at t h o se wh o h ad b een p revio u sly exp o sed t o TB p at ien t s were m o re in t erest ed in p a rt icip a t in g . Silva(3 ),
TABELA 4
Resultados da análise multivariada (reg ressão log ística) de 1 4 0 alunos de
Medicina; Campos (RJ), 2 0 0 2
PT + RC p va lo r IC 9 5 %
EFF 1,00 0,61 0 ,9 9 – 1 ,0 2
BCG < 4 anos 3,99 0,05 0 ,9 9 – 1 5 ,9 9
PP 5,20 0,06 0 ,9 6 – 2 8 ,0 7
Th e au t h o rs d o n o t m en t io n wh et h er an y verb al o rien t at io n was g iven t o t h e st u d en t s in vo lved . In t he cu rren t st u dy, we were afforded t he opport u n it y t o exp lain t h e q u est io n n aire an d it s o b ject ives t o t h e m ed ical st u d en t s at t h e FMC. We g ave t h ese lect u res t o as m an y st u d en t s as p o ssib le.
Th e est im a t ed p reva len ce o f Mt b in fect io n a m o n g t h e g en era l p o p u la t io n in t h e Am erica s (exclu d in g t h e USA an d Can ad a) is 2 5 %(1 ). Th e
resu lt o f t h e cu rren t st u d y (TST p o sit ivit y rat e o f 7 .9 %) m ay b e d u e t o t h e fact t h at t h e su b ject s were yo u n g an d o f h ig h er so cio eco n o m ic st at u s t h an t h e g en eral p o p u lat io n .
Du e t o t h e m ag n it u d e o f t h e TB ep id em ic in Br a z il, p u b lic h e a lt h p o lic ie s p r io r it iz e t h e id en t ifica t io n a n d a p p ro p ria t e t rea t m en t o f TB p at ien t s. Lit t le o r n o em p h asis is p laced o n t h e p reven t io n o f TB t ran sm issio n am o n g m ed ical o r n u rsin g st u d en t s in h ealt h cen t ers t h at are u sed for t heir t rain in g. Consequ en t ly, TST admin ist rat ion is n o t st a n d a rd p ra ct ice in m ed ica l o r n u rsin g sch o o ls.
Sim ila r st u d ies sh o u ld b e co n d u ct ed in o t h er p u b lic a n d p riva t e m e d ica l sch o o ls in Bra z il. It is releva n t t o p o in t o u t t h a t lo n g it u d in a l st u d ies p r o vid e in f o r m a t io n r e g a r d in g t h e r is k o f n o so co m ial in fect io n am o n g m ed ical an d n u rsin g st u d en t s. Th e resu lt s o f t h e p resen t st u d y, a s well a s t h o se fro m o t h er recen t st u d ies co n d u ct ed in Bra z il(3 , 11 , 1 3 ), s t ro n g ly s u g g e s t t h a t m e d ic a l
st u d e n t s sh o u ld u n d e rg o a t le a st o n e TST u p o n en t ry in t o u n iversit y a n d a n o t h er a ft er b eg in n in g t h eir clin ica l t ra in in g , a n d t h a t ch em o p ro p h yla xis is in d ica t e d in ca se s o f t u b e rcu lin co n ve rsio n , wit h o r wit h o u t a ct ive TB. Th is reco m m en d a t io n is in co m p lia n ce wit h t h e g u id elin es est a b lish ed b y t h e Ce n t e r s f o r D i s e a s e Co n t r o l a n d Pre ve n t io n(7 ), t h e In t e rn a t io n a l Un io n Ag a in st
Tu b ercu lo sis a n d Lu n g Disea ses(1 8 ) a n d t h e Wo rld
Hea lt h Org a n iza t io n(1 9 ).
Th e h ig h p ercen t a g e o f n eg a t ive TSTs a m o n g m ed ica l st u d en t s a t t h e b eg in n in g o f t h e co u rse
t h a t w o u ld e it h e r va lid a t e o r in va lid a t e t h e re c o m m e n d a t io n f o r BCG re - va c c in a t io n o f h e a lt h p ro fe ssio n a ls (wo rkin g in a n y t yp e o f h e a lt h ca re fa cilit y) wh o t e st n e g a t ive o n t h e ir first a n d se co n d TSTs. In a d d it io n , o p e ra t io n a l st u d ie s t h a t co u ld o p t im iz e t h e t re a t m e n t o f l a t e n t TB i n t h e s e i n d i v i d u a l s s h o u l d b e p ro m o t ed .
Fu rt h erm o re, we su g g est t h at an alysis o f TST posit ivit y rat es amon g gradu at e st u den t s in clin ical t rain in g at u n iversit y h o sp it als m ay b e a u sefu l in d icat o r in m o n it o rin g t h e im p act o f t h e d iverse b io sa fet y m ea su res a d o p t ed d u rin g t h e va rio u s t rain in g periods.
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