Intro To Screening Flashcards
LO2: list criteria for implem a screen prog, incl those rel to the cond.
-4 criteria for screen progs- dis, test, tx, prog.
Dis/cond: must imp health prob. Epidem and nat hx understood. Early detectab stage. Cost effec prim interven been consid and implem where poss.
LO2: those rel to the test.
-Test: simp and safe. Precice and valid. Acceptab to pop. Distrib test vals in pop known ie prop test pos and neg. cut off lev defined for pos. Policy on who to investig furth.
-any screen prog makes 2 types err.
Refer well peop for investig= anx, inconven, direct and opp cost. FALSE POS.
Fail to refer peop with dis= inapp reassurance, delay presentat with symps. FALSE NEG.
-feats of test validity- sensitiv (detec rate), specifcity, pos perdictive val, meg predictive val.
Test validty- true positives, false negs, false pos, true neg.
sensitiv: propor with dis who test pos. Aka detec rate. Is probab a case will test pos. CALC. High good.
Specif: propor w/o dis who test neg. is probab a non cade will test neg. CALC. High good.
Sensit and specif are func of chars of the test. When same test applied in same way in diff pops the test will have same sensit and specif.
Pos predictive val: probab that someone who tested pos has the dis. Strongly infl by dis preval. CALC. Low preval dis has lower PPV.
Neg predictive val: propor who test neg and really dont have dis. CALC.
-implics of false pos- says pt may have dis when dont. Offered invasive risky test. Poss lower upt screening in fut and greater risk interval CA. If PPV low then lot false pos people stress and unnecess proced.
-implics false neg- not off tests when would benef. undiag. False reassur and may present late with symps.
LO2: those rel to tx.
-effective ev based tx must be avail.
Earl tx must be an adv.
Agreed policy on who to treat.
Clinic managem and pt outcome should be optimised in HC providers bef particip in screen prog.
LO2: those rel to prog.
-proven efefctiven, pref RCT data.
Qual assurance for whole prog not just test.
Facils for counselling.
Facils for diag and tx.
-other options consid eg impr tx.
Think about opport costs.
Decis about params shoud be sci justifiab to public.
Benef should outweigh physic and psych harm.
LO3: list advs and disadvs of screen for dis.
-should fulfill cert criteria.
Expensive and divert resource.
Risks.
Need to be eval acc to internat accepted princips.
LO1: define screening.
-detec of dis- spont present, opport case finding, screening.
Spont- person present with symps, self defined as pt. GP, AE etc. A diag is made.
Opport- present with symps rel to a dis/prob. HCP takes opp to check for other probs eg BP, dipstick.
Diag- definit ID of suspected dis or defect by applic of tests, examins or other proceds (can be extensive) to definitely label people as having dis or not.
Proc of diag- presentat. Hx, examin, tests. Dis or not. Tx follows. Pt will be prep to accept risks assoc with tx in order to get well.
-screeing= systematic attempt to detec unrecog cond by applic of tests, examins or other proceds which can be applied rap and cheaply to disting btw appar well peop who probab have dis (or precurs) and those who prob dont.
Process- screening test. Screen pos= high risk. Neg= low risk. If pos then do diag tests to see if dis or not.
Foll screening person labelled as screen pos, not mean they defin have dis. Furth tests req bef diag. Tx only once definitiv diag.
Is screen good as earlier diag and tx?
Screening= pub health service where mems of defined pop who dont necess perceive theyre at risk or are already aff by a dis or its complics, are asked a Q or off a test to ID those more likely to be helped than harmed by furth tests or tx to reduce risk of dis or its complics.
Purp- better outcome vs finding someth usual way. If tx can wait til symps then no pt. finding someth earlier not prim objective.
Egs- mammography. AAA men 65 US= reduc risk death from rupt by half, ST decr QoL for tx, psych dam of knowing have aneur.
No nat screen for prostate CA, breast CA under 50, cervic CA under 25.
