Using SNOMED CT as a Mediation Terminology: Mapping Issues, Lessons

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Using SNOMED CT as a M e diation T e rminology : Mapping Issu e s, L e ssons L e arn e d, and N e xt St e ps Toward Achi e ving S e mantic Int e rop e rability Sarah Mauld e n, MD, MS 1 , Patty Gr e im, RN, MS 1, Omar Bouhaddou, PhD 1,2 , Pradnya Warn ek ar, RPh, MS 1,3 , Laura M e gas 4 , Fola Parrish, PharmD 5 , Micha e l J . Lincoln, MD 1, 6 1 D e partm e nt of V e t e rans Affairs, V e t e rans H e alth Administration, Chi e f H e alth Informatics Offic e , Salt La ke City, UT 2 El e ctronic Data Syst e ms, Plano, TX 3 dNovus RDI, San Antonio, TX 4 Northrop Grumman Corporation, Chantilly, VA 5 D e partm e nt of D e f e ns e , Tricar e Manag e m e nt Activity, Falls Church, VA 6 D e partm e nt of Biom e dical Informatics, Univ e rsity of Utah, Salt La ke City, UT sarah.mauld e n @ ... more. less.

va.gov , patricia.gr e im @ va.gov ABSTRACT Th e Clinical Data R e pository / H e alth Data R e pository (CHDR) proj e ct is a combin e d e ffort of th e D e partm e nt of V e t e rans Affairs (VA) and th e D e partm e nt of D e f e ns e (DoD) to e xchang e clinical information b e tw ee n our El e ctronic H e alth R e cords (EHR). CHDR e xchang e s standardi ze d, computabl e data, as oppos e d to t e xtual data that is only human r e adabl e . CHDR utili ze s m e diation t e rminologi e s for h e alth data e xchang e . For all e rgy r e actions data, CHDR us e s SNOMED CT in conformanc e with H e alth Information T e chnology Standardi z ation Pan e l (HITSP) r e comm e ndations. This pap e r r e ports how w e impl e m e nt e d this solution. Busin e ss rul e s for mapping all e rgy r e actions w e r e e stablish e d jointly. Each ag e ncy ind e p e nd e ntly mapp e d its l e gacy data to th e sam e v e rsion of SNOMED CT. CHDR has sinc e b ee n impl e m e nt e d in s e v e n locations wh e r e VA and DoD hav e joint pati e nt car e e nvironm e nts. Statistics on actual pati e nt data from F e bruary-Jun e 2007 show e d a 74-99% m e diation succ e ss rat e for all e rgy r e actions data. Examination of m e diation failur e s e xpos e d issu e s r e lat e d to mapping and SNOMED CT conc e pt mod e ling. In addition, w e e mphasi ze th e significanc e of adh e r e nc e to a d e tail e d t e rminology m e diation strat e gy, d e sirability of a standard SNOMED CT- bas e d subs e t for all e rgy r e actions, and th e cr e ation of this subs e t for publication and distribution. INTRODUCTION Th e Pr e sid e nt has ord e r e d F e d e ral ag e nci e s to promot e improv e d h e althcar e quality and e ffici e ncy through s e cur e and standard-bas e d data e xchang e 1 . Wh e n clinicians e xchang e data, int e rop e rabl e m e aning is possibl e b e caus e clinicians shar e structur e s of clinical practic e and familiar clinical languag e 2 . Similarly, m e aningful e l e ctronic data e xchang e r e quir e s a shar e d structur e for transmission and a common e l e ctronic vocabulary 3 , which yi e lds Computabl e S e mantic Int e rop e rability (CSI) 4 . CSI mak e s ord e r ch e cks and e l e ctronic al e rts possibl e across institutions, and is an e ss e ntial compon e nt of a longitudinal EHR that prot e cts pati e nt saf e ty. Th e CHDR proj e ct is a Congr e ssionally-mandat e d, combin e d e ffort which aims to e xchang e standardi ze d, computabl e data, as oppos e d to t e xtual data that is only human r e adabl e . Computabl e data e xchang e e nabl e s cs e mantic int e rop e rability d and p e rmits utili z ation of e l e ctronic d e cision support tools on th e sum of local and r e mot e data at e ith e r ag e ncy 6 . CHDR curr e ntly e xchang e s pharmacy and all e rgy data e l e m e nts and th e ag e nci e s ar e working to shar e laboratory data e l e m e nts by th e e nd of fiscal y e ar 2008. CHDR has inform e d th e H e alth IT Standards Pan e l (HITSP) that d e signat e s int e rop e rability standards for EHRs. VA and DoD us e diff e r e nt int e rnal data standards for all e rgi e s, and und e r CHDR utili ze a common, HITSP-sp e cifi e d m e diation t e rminology. CHDR e xchang e s pharmacy, drug all e rg e ns, and all e rgy r e actions, and will soon e xchang e laboratory (ch e mistry/h e matology) data. CHDR e xchang e of compr e h e nsiv e pharmacy information 7 and drug all e rgy r e actant information 8 hav e b ee n w e ll d e scrib e d. Representing and sharing knowledge using SNOMED Proceedings of the 3rd international conference on Knowledge Representation in Medicine (KR-MED 2008) R. Cornet, K.A. Spackman (Eds) 85 2 Th e CHDR strat e gy for e xchang e of all e rgy r e actions (signs and symptoms) data us e s SNOMED CT, in conformanc e with Consolidat e d H e alth Informatics (CHI) and now HITSP r e comm e ndations. W e now r e port how VA and DoD hav e us e d SNOMED CT succ e ssfully as a m e diation t e rminology, and d e scrib e th e r e sults. METHODS Initial work for all e rgy r e actions und e r th e m e diation approach includ e d th e commitm e nt at e ach ag e ncy to normali ze l e gacy t e rms, using a list of c e ntrally maintain e d conc e pt t e rms 9 . All e rgy r e actions w e r e compris e d primarily of signs and symptoms, but could also includ e disord e rs or clinical conditions attributabl e to e xposur e to a drug r e actant. Each ag e ncy mapp e d its l e gacy all e rgy r e actions data to SNOMED CT 10 . Th e four-part t e rminology m e diation strat e gy was outlin e d as follows 11 : 1.S e l e ct a m e diation t e rminology compliant with CHI/HITSP standards (if possibl e ). 2.Map e ach ag e ncy 9s t e rms to conc e pts within th e m e diation standard. 3.Exchang e th e m e diation cod e s. 4.Coordinat e cont e nt maint e nanc e plans. Tabl e 1 shows th e CHI standard t e rminologi e s and r e l e as e s d e signat e d for th e four domains at th e start of th e CHDR proj e ct. Busin e ss rul e s for mapping all e rgy r e action l e gacy t e rms to SNOMED CT conc e pts w e r e d e v e lop e d jointly 12 . For e xampl e , SNOMED CT hi e rarchi e s w e r e prioriti ze d in ord e r of pr e f e r e nc e for mapping as follows : 1) Findings, 2) Disord e rs, 3) Morphologic abnormality, 4) Obs e rvabl e e ntity, 5) Cont e xt D e p e nd e nt Cat e gory. Mappings from sp e cific to mor e g e n e ral t e rms (and vic e v e rsa) w e r e avoid e d, b e caus e of th e bidir e ctional natur e of th e data e xchang e . For instanc e , mapping cnasal burning d to cburning s e nsation of mucous m e mbran e (finding) d cr e at e s e ith e r a loss of th e clinical d e tail cnasal d wh e n translat e d (for an outbound m e ssag e ), or forc e s th e translation of a g e n e ral t e rm cmucous m e mbran e d to a sp e cific on e -- cnasal d--(for an inbound m e ssag e ). Local t e rms not found in SNOMED CT w e r e coll e ct e d forpot e ntial submission to th e SNOMED d e v e lopm e nt organi z ation. Oth e r mapping rul e s gov e rn e d missp e llings, qualifi e rs, synonyms, ambiguous t e rms, and outdat e d t e rms. Tabl e 2 shows a sampl e of VA all e rgy r e action t e rms with th e ir VA uniqu e id e ntifi e rs (VUIDs) and SNOMED CT mappings. Onc e mapping rul e s w e r e e stablish e d, t e rminologists at e ach ag e ncy manually mapp e d all e rgy r e action t e rms to SNOMED CT. VA us e d Ap e lon 9s T e rmWorks tool and SNOMED 9s CliniClu e ® brows e r, and DoD us e d th e T e rminology S e rvic e Bur e au (TSB) and th e CliniClu e ® brows e r. Table 1 . CHDR Domains and D e signat e d Standards . Domain M e diation T e rminology (CHI Standard) Pharmacy RxNorm Jun 2005 Drug All e rg e ns UMLS Jan 2005AA All e rgy R e actions SNOMED CT Jan 2005 Lab (Ch e mistry & H e matology) LOINC 2.14 Jan 2005 Table 2. VA Uniqu e Id e ntifi e rs, All e rgy R e action T e xt, and Corr e sponding SNOMED CT Mappings. VUID VUIDT e xt SNOMED CT ID SNOMED CT T e xt 4637123 BLISTER 339008 Blist e r of skin AND/OR mucosa (finding) 4543527 ORTHOSTASIS 271648003 Postural drop in blood pr e ssur e (finding) 4696326 ASEPTIC NECROSIS OF BONE 398199007 As e ptic n e crosis of bon e (disord e r) 4538635 RASH 271807003 Eruption of skin (disord e r) 4538640 SEI Z URES 91175000 S e i z ur e (finding) 4539274 NOSEBLEED 249366005 Bl ee ding from nos e (finding) Representing and sharing knowledge using SNOMED Proceedings of the 3rd international conference on Knowledge Representation in Medicine (KR-MED 2008) R. Cornet, K.A. Spackman (Eds) 86 3 For mapping validation of all e rgi e s t e rms (both r e actions and r e actants), two r e vi e w e rs conduct e d thr ee s e parat e r e vi e ws (10 hours e ach for a total of 60 e xp e rts 9 hours) and id e ntifi e d various discr e panci e s in about 5% of th e total numb e r of t e rms. All discr e panci e s w e r e corr e ct e d 13 . An ind e p e nd e nt r e vi e w of conc e pts common to both ag e nci e s was p e rform e d to e nsur e accurat e translation and calculat e e xp e ct e d m e diation succ e ss rat e s 14 . S ee Tabl e 3. T e rminology ctranslation d and cm e diation d ar e d e scrib e d as follows by Bouhaddou e t al. : cTh e m e diation succ e ss rat e d e fin e s th e p e rc e ntag e of data in on e syst e m that is und e rstood and computabl e by th e oth e r syst e m. For e ach dir e ction of th e data e xchang e , inbound or outbound, th e r e is a diff e r e nt m e diation succ e ss rat e . For m e diation to succ ee d, two translations hav e to b e succ e ssful. First, th e sourc e ag e ncy has to translat e from its vocabulary to th e m e diation t e rminology. Th e n, th e targ e t ag e ncy has to translat e from th e m e diation t e rminology to its nativ e vocabulary without loss of m e aning 15 . d M e diation succ e ss rat e s ar e calculat e d by multiplying th e translation succ e ss rat e s of e ach ag e ncy. Wh e n cod e d m e diation fails, th e CHDR proj e ct e xchang e s all e rgy r e action data as t e xt without a m e diation cod e . RESULTS T e rminology translation and m e diation statistics w e r e compil e d for all e rgy r e actions data during a 5-month p e riod in 2007. Th e numb e rs of translation and m e diation att e mpts fluctuat e d from month to month, but g e n e rally show e d an incr e asing tr e nd as th e proj e ct was impl e m e nt e d at additional sit e s ov e r th e 5-month tim e fram e . Tabl e 4 shows translation and m e diation succ e ss rat e s for all e rgy r e actions s e nt from VA to DoD. Tabl e 5 shows statistics for all e rgy r e actions s e nt from DoD to VA. Ov e rall, m e diation succ e ss rat e s vari e d from 74% to 99%. Table 3 . Common and Uniqu e All e rgy R e action Conc e pts D e t e rmin e d by Each Ag e ncy Mapping to SNOMED CT. Ag e ncy Total Common T e rms Mapp e d T e rms Uni q u e to Each Ag e ncy Unmapp e d T e rms VA 346 299 25 (7%) 22 (6%) DoD 456 299 47 (13%) 110 (24%) Table 4 . VA-to-DoD M e diation Statistics for All e rgy R e actions, F e b-Jun e 2007. * VA-to-DoD F e bruary March April May J un e Total VA-to-SNOMED CT translation att e mpts 168 193 338 959 502 Translation failur e s (VA-to-SNOMED CT) 4 0 1 13 1 Total VA all e rgy r e actions s e nt to DoD 164 193 337 946 501 Translation Succ e ss Rat e: VA-to-SNOMED CT 98 % 100 % 100 % 99 % 100 % Total all e rgy r e actions r e c e iv e d by DoD 164 193 337 946 501 Translation failur e s (SNOMED CT-to-DoD) 17 17 34 121 5 Total VA all e rgy r e actions s e nt to DoD CDR 147 176 303 825 496 Translation Succ e ss Rat e: SNOMED CT-to- DoD 90 % 91 % 90 % 8 7% 99 % MEDIATION S UCC ESS R ATE: V A - to - DoD 88% 9 1 % 90% 86% 99% * Y e llow ar e as d e signat e translation s e rvic e s p e rform e d by VA. Whit e ar e as d e signat e translation s e rvic e s p e rform e d by DoD. CDR = Clinical Data R e pository. Representing and sharing knowledge using SNOMED Proceedings of the 3rd international conference on Knowledge Representation in Medicine (KR-MED 2008) R. Cornet, K.A. Spackman (Eds) 87 4 Table 5 . DoD-to-VA M e diation Statistics for All e rgy R e actions, F e b-Jun e 2007. * DoD-to-VA F e bruary March April May J un e Total DoD-to-SNOMED CT translation att e mpts 1,509 1,788 2,025 3,521 4,030 Translation failur e s (DoD-to-SNOMED CT) 306 467 432 432 107 Total all e rgy r e actions s e nt to VA 1,203 1,321 1,593 3,089 3,923 Translation Succ e ss Rat e: DoD-to-SNOMED CT 80 % 7 4 % 7 9 % 88 % 9 7% Total all e rgy r e actions r e c e iv e d by VA 1,203 1,321 1,593 3,089 3,923 Translation failur e s (SNOMED CT-to-VA) 1 0 8 11 69 Total DoD all e rgy r e actions s e nt to VA HDR 1,202 1,321 1,585 3,078 3,854 Translation succ e ss rat e: SNOMED CT-to- VA 100 % 100 % 99 % 100 % 98 % MEDIATION S UCC ESS R ATE: DoD - to -V A 80% 7 4 % 78% 87% 96% * Y e llow ar e as d e signat e translation s e rvic e s p e rform e d by VA. Whit e ar e as d e signat e translation s e rvic e s p e rform e d by DoD. HDR = H e alth Data R e pository. Analysis of th e caus e s of th e m e diation failur e s r e v e al e d th e following issu e s, list e d in ord e r of fr e qu e ncy of occurr e nc e: 1.SNOMED CT conc e pt mod e ling issu e s w e r e e xpos e d. For e xampl e , a s e arch for cnos e bl ee d d in SNOMED CT 9s CliniClu e ® brows e r r e turns mor e than on e option within th e cfinding d hi e rarchy : cbl ee ding from nos e d vs. cnos e bl ee d/ e pistaxis symptom. d Anoth e r e xampl e of a mod e ling issu e: th e cSituation with Explicit Cont e xt d hi e rarchy was not addr e ss e d in th e original VA/DoD mapping rul e s, as this hi e rarchy e volv e d within SNOMED CT aft e r th e initiation of th e mapping. 2.N e w l e gitimat e all e rgy r e action t e rms w e r e add e d ind e p e nd e ntly within e ach ag e ncy, which l e d to m e diation failur e s in th e tim e int e rval b e tw ee n synchroni z ation and updating of e ach ag e ncy 9s fil e s. 3.Maint e nanc e and v e rsioning issu e s e m e rg e d wh e n SNOMED CT r e l e as e d n e w v e rsions with n e w conc e pt status e s ( e .g., c e rron e ous d, climit e d d, cduplicat e d, cambiguous d) during th e proj e ct. If ag e ncy updat e s w e r e not synchroni ze d, m e diation failur e s would r e sult. 4.All e rgy r e action conc e pts and t e rms w e r e som e tim e s d ee m e d appropriat e by on e ag e ncy but not th e oth e r. For e xampl e , th e conc e pt csyst e mic dis e as e d was us e d at on e ag e ncy, but th e oth e r ag e ncy f e lt this t e rm add e d no valuabl e information about an all e rgic r e action and did not includ e it in its list of s e l e ctabl e r e actions for us e by provid e rs. 5.Div e rg e nt approach e s to SNOMED mapping e xist e d b e tw ee n VA and DoD, d e spit e shar e d busin e ss rul e s. For instanc e , chyp e rt e nsion d was mapp e d to cfinding of incr e as e d blood pr e ssur e (finding) d at on e ag e ncy, and to cHyp e rt e nsiv e disord e r, syst e mic art e rial (disord e r) d at th e oth e r. DISCUSSION W e b e gin with a list of l e ssons l e arn e d. 1. Mapping rul e s must always b e tailor e d to th e sp e cific purpos e of th e mapping. Th e s e rul e s may b e influ e nc e d by non-t e rminological issu e s, such as th e pot e ntial for th e e ntir e m e ssag e to fail if on e compon e nt fails. W e must r e cogni ze that mappings ar e oft e n purpos e - or us e cas e -driv e n, as w e ll as built by s e mantic nuanc e s of cont e xt. 2. Ev e n with e stablish e d rul e s in plac e , th e r e is a cl e ar n ee d for continu e d communication b e tw ee n ag e nci e s. W e w e r e unabl e to disc e rn any major consist e nt r e ason for th e mapping rul e violations. On e possibility is that VA and DoD initially us e d Representing and sharing knowledge using SNOMED Proceedings of the 3rd international conference on Knowledge Representation in Medicine (KR-MED 2008) R. Cornet, K.A. Spackman (Eds) 88 5 diff e r e nt mapping tools. Anoth e r is that th e proc e ss of finding th e corr e ct map for a t e rm is variabl e and influ e nc e d by syntax and linguistic f e atur e s of th e s e arch e ngin e . In s e v e ral cas e s, th e Clu e brows e r yi e lds an appar e ntly corr e ct r e sult (for e xampl e , a s e arch for corthostatic hypot e nsion d r e turns corthostatic hypot e nsion (disord e r) d) but th e t e rm is locat e d in th e disord e r hi e rarchy, rath e r than th e findings hi e rarchy (to b e us e d in pr e f e r e nc e if possibl e ). It may not b e imm e diat e ly appar e nt that an alt e rnativ e mapping e xists ( cpostural drop in blood pr e ssur e (finding) d) in anoth e r hi e rarchy. Th e clinical knowl e dg e , background, and familiarity with SNOMED hi e rarchi e s and f e atur e s of CliniClu e ® also ar e lik e ly to influ e nc e s e arch r e sults. Id e ally, a common t e am, proc e ss, and tools e t would b e us e d to produc e th e mapping. P e rhaps th e mapping could b e com e a s e rvic e of th e Standards D e v e lopm e nt Organi z ation, as is th e cas e with RxNorm. 3. SNOMED CT mod e ling issu e s w e r e probably th e most difficult to addr e ss, as th e s e r e quir e a sophisticat e d knowl e dg e of conc e pt mod e ling and of th e e volution of SNOMED hi e rarchi e s ov e r tim e . 4. Maint e nanc e plans for using m e diation t e rminologi e s n ee d to includ e sp e cific plans for synchroni z ing updat e s to th e standard r e f e r e nc e t e rminology, in this cas e SNOMED CT, and also for synchroni z ing updat e s to e ach ag e ncy 9s mapping fil e . A significant outcom e of this proj e ct is th e g e n e ration of a n e w, uniqu e SNOMED CT subs e t sp e cific for All e rgy R e actions (signs and symptoms) which could pot e ntially b e submitt e d for inclusion in SNOMED CT as an official subs e t. It could also b e publish e d and shar e d among f e d e ral ag e nci e s and non-f e d e ral partn e rs. In D e c e mb e r 2007, HITSP d e signat e d th e VA/Kais e r P e rman e nt e (KP) Probl e m List subs e t (16,430 e ntri e s) as th e r e comm e nd e d standard for all e rgy r e actions, a d e partur e from pr e vious CHI r e comm e ndations to us e th e VA/DoD All e rgy R e actions subs e t (864 e ntri e s) 16 . Whil e many of th e VA/DoD All e rgy R e actions t e rms ar e contain e d within th e Probl e m List subs e t, us e of th e Probl e m List subs e t to r e cord all e rgy r e actions (signs and symptoms) may prov e probl e matic, as is th e cas e wh e n e v e r data is us e d for a purpos e oth e r than that originally int e nd e d. Consid e r th e t e rms ccircumoral par e sth e sia (finding) d and c e d e ma of pharynx (disord e r). d Th e s e t e rms ar e appropriat e ly found within th e VA/DoD All e rgy R e actions subs e t, but not within th e VA/KP Probl e m List subs e t. Th e sh ee r si ze and compl e xity of th e Probl e m List subs e t, compar e d to that of th e All e rgy R e actions subs e t, may unn e c e ssarily complicat e data e ntry for provid e rs and r e sult in unwant e d e ntry of inappropriat e t e rms as All e rgy R e actions. Th e small e r subs e t could e nabl e mor e pr e cis e data constraints and gr e at e r computing sp ee d, without sacrificing data int e grity. Communication with HITSP is ongoing r e garding this issu e . W e propos e that a n e w study b e und e rtak e n to e valuat e th e VA/KP Probl e m List and compar e it to th e VA/DoD All e rgy R e action subs e t, docum e nting cont e nt gaps, ar e as of ov e rlap, and suitability for us e as a m e diation t e rminology. In conclusion, w e point out that th e e xp e ns e of mapping VA 9s and DoD 9s l e gacy t e rms (and maint e nanc e of sam e ) was r e lativ e ly substantial 4 e v e n for th e limit e d list of All e rgy R e actions. As CHDR e xpands to includ e mor e VA and DoD sit e s, th e t e rminology maint e nanc e r e quir e m e nts will continu e . Adopting th e HITSP standard int e rnally as a r e pr e s e ntation for all e rgi e s and r e actions would b e a mor e e ffici e nt m e thod of working toward tru e s e mantic int e rop e rability. Using a phas e d approach, l e gacy t e rms can b e mapp e d to th e standard, pr e s e nt e d for adoption by th e Standards D e v e lopm e nt Organi z ation (SDO), and e v e ntually migrat e d to th e standard r e pr e s e ntation its e lf with d e pr e cation of invalid l e gacy t e rms. Th e us e of m e diation t e rminologi e s for computabl e data e xchang e is a dynamic and e volving proc e ss. It is pron e to pitfalls, but is an e ff e ctiv e , practical m e thod for advancing th e goal of s e mantic int e rop e rability. 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