1500
`
`THE NEW ENGLAND JOURNAL OF 1\IEDICINE
`
`.June 7, 1984
`
`NEUROLOGIC OUTCOME IN CHILDREN WITH INBORN ERRORS OF UREA SYNTHESIS
`Outcome of Urea-Cycle Enzymopathies
`MicHAEL MsALL, M.D., MARK L. BATSHAW, M.D., RICHARD Suss, M.D., SAUL W. BRtJSILOW, M.D.,
`AND E. DAviD MELLITs, Sc.D.
`
`Abstract We studied 26 children with inborn errors of
`urea synthesis who survived neonatal hyperammonemic
`coma. There was a 92 per cent one-year survival rate
`associated with nitrogen-restriction therapy and stimula(cid:173)
`tion of alternative pathways of waste nitrogen excretion.
`Seventy-nine per cent of the children had one or more
`developmental disabilities at 12 to 74 months of age; the
`mean IQ was 43±6. There was a significant negative lin(cid:173)
`ear correlation between duration of Stage Ill or IV neonatal
`hyperammonemic coma and IQ at 12 months (r = -0.72,
`
`P<0.001) but not between the peak ammonium level (351
`to 1800 p,M) and 10. There was also a significant correla(cid:173)
`tion between CT abnormalities and duration of hyperam(cid:173)
`monemic coma (r = 0.85, P<0.01) and between CT ab(cid:173)
`normalities and concurrent IQ (r = -0.75, P<0.02).
`These results suggest that prolonged neonatal hyperam(cid:173)
`monemic coma is associated with brain damage and im(cid:173)
`pairment of intellectual function. This outcome may be
`prevented by early diagnosis and therapy. (N Engl J Med
`1984; 310:1500-5.)
`
`I NHERITED deficiencies of each of the live en(cid:173)
`
`zymes of the urea cycle have been described. The
`overall prevalence is estimated to be I in 30,000 live
`births. Unable to excrete waste nitrogen as urea, af~
`kcted infants accumulate ammonia and other nitroge(cid:173)
`nous compounds. Children born with a complete defi(cid:173)
`ciency of one of the urea-cycle enzymes (apart from
`arginase deficiency) appear normal during the first 24
`hours of life, but by one week of age symptoms of
`hypcrammonemia develop. These include feeding in(cid:173)
`tolerance, vomiting, lethargy, respiratory distress, sei(cid:173)
`zures, and coma. Previous therapy included modifi(cid:173)
`cation of the quality and quantity of dietary nitrogen
`and was associated with a 14 per cent one-year surviv(cid:173)
`al rate. 1
`We have proposed combining nitrogen restriction
`with the stimulation of alternative pathways of waste
`nitrogen excretion (Fig. I). Although urea is the nor(cid:173)
`mally excreted waste nitrogen product, other nitroge(cid:173)
`nous compounds may be synthesized and excreted.
`Two dasses or such non urea nitrogenous metabolites
`are th<' cytosolic urea-cycle intermediates and certain
`amino acid acylation products. In derccts orarginino(cid:173)
`succinate synthetase (citrullinemia) and argininosuc(cid:173)
`cinase ( argininosuccinic acid uri a), the synthesis and
`excretion or citrulline and argininosuccinic acid as
`waste nitrogen products may be promoted by dietary
`arginine supplementation. The amino acid acylation
`products of sodium benzoate and sodium phenylace(cid:173)
`tate (hippurate and phenylacctylglutamine, respec(cid:173)
`tively) may substitute (()r urea nitrogen excretion in all
`urea-cycle del(·cts.
`We have used alternative-pathway therapy to treat
`~6 children with urea-cycle enzyme deficiencies.~
`There has been a 92 per cent one-year survival rate.
`The neurologic and developmental outcomes in these
`
`From I he Deparlmcms of Pediatrics and Ncuroradiology and lhc John F. Ken(cid:173)
`nedy ln,titute, Johns Hopkins Medical lnslilutions, Bal!irnorc. Address rcprinl
`requests to Dr. llatshaw at the John F. Kennedy lnslitutc, 707 N. Broadway,
`Ballirnorc. MD 21205.
`Supponcd by grants (HD 109K I and HD 11134) from the National Institute' of
`Health. Dr. Batshaw is a Joseph P. Kennedy, Jr., Scholar.
`
`children at ages 12 to 74 months (mean, 31) are IT(cid:173)
`ported hen~. Most or the children were handicapped.
`There was a significant negative linear correlation be(cid:173)
`tween duration of neonatal hyperammonemic coma
`and IQ at 12 months. Significant relationships were
`also f(ll!nd between abnormalities identified by CT
`scans or the brain and duration or neonatal hyperam(cid:173)
`nwnemic coma and between CT abnormalities and
`IQ score.
`
`Subjects
`
`METHODS
`
`Twenly-six children wilh cornplcle urea-cycle cnzynH' ddici<·li·
`des were identified lwcaust' of' rwonatal hypt·rantntoiH'Jllic <·onta;
`carbamyl phosphate synllwtasc was <kfici<·nt in three, omithitll'
`transcarharnylast· in sev<·n, argininosucdnatt· syntlwtas<· in ei~ht,
`and ar~-:ininosuccinas<' in dglll. Two of the male infimts with a
`deficiency of ornithine transcarbamylm)(' died of hypentnunoru·mic
`coma ))('!(on· one year of age, bu1 I he olher :11 palienls (!12 pn n·nl)
`surviv<·d. These 21 children were sludied ncurolo>(ically and <kvcl(cid:173)
`opna·nlally.
`
`Laboratory Methods
`
`. VVe have previously described our protocol t<Jr I he managcmr•tll of
`hypcnlllllllOJH'nlk con1a and lon~-tcnn thcrnpy using alternative
`palhways of wasle nitrogen excretion." The cntTr·nt managcnwnt
`protocol is summarized in Table I. In addition to sodium bcnzoal<',
`W<' hav<· recently ad<kd sodium phenylacelalc to I real deficiencies of
`carbamyl phosphate syntlu·laSt', omilhim· lranscarbamylasc, and in
`sonw cases argininosucdnatc synthetase. Vv'l' also now suln.;titutt'
`citrulline fin· arginin<' as an t'Sscntial tunino add in patients with
`carbamyl phosphate syntlwtasc or ornithin(' transcarhamylase defi(cid:173)
`ciency.
`Plasrna anunoniurn lt-v('ls W<"l"(' nH~asurcd cith<'r by an t•nzyniat(cid:173)
`ic method, using glulamate dchydrop;cnase,"1 or hy a calion-cx(cid:173)
`chan~<'-r<'sin lllt.'thod.:i Nonnal plasnta aJn1noniun1 levels, a<'cord~
`ing lo these methods, arc 15 to :i5 J.~-M (~0 to :,o p,g J"'r clccililcr).
`
`Definitions
`
`Dural ion of coma was defined as lhc ntnnlH'r of days sp<'llt in
`S1age I II or Stage IV coma. '• Slagc II I coma was ddi~tcd as utu·on(cid:173)
`sl'iousru·ss with dt•ct·n·hratc posture and withdrawal rcspoust' to
`painful slimuli. Slagc IV coma was ddincd as flaccid low· with
`dilalcd unn•spollsive pupils alld no response to paillfitl stimuli.
`Menial rclardation'' was ddincd as an ICJtmdr·r 70. Cerebral palsy
`was dcfinr·d as a delay in attainmcnl ofntotor milt·slotws assodalcd
`
`The New England Journal of Medicine
`Downloaded from nejm.org by RHEANNA HAFNER on June 29, 2018. For personal use only. No other uses without permission.
`From the NEJM Archive. Copyright© 2010 Massachusetts Medical Society. All rights reserved.
`
`Par Pharmaceutical, Inc. Ex. 1008
`Par v. Horizon, IPR of Patent No. 9,561,197
`Page 1 of 6
`
`

`

`Vol. 310 No. 23
`
`INBORN ERRORS OF UREA SYNTHESIS MSALL ET AL.
`
`1501
`
`during a period of normal or nt'arly normal
`ammonium levels (<60 ~Il\1). Psvchomt'tric
`testing was generally repeated ,;t 6- 10 12-
`month intervals.
`
`Computed Tomography
`
`benzoylyc1ne
`
`I h1ppurote I
`
`\
`
`Hco;
`
`carbamyl phosphate
`
`ore
`
`ornithme
`
`· -- · : \
`~ u!e .. o ~ .
`~~~~
`
`/
`
`§~
`Asi..
`aspartate
`I argmmosucclnote I
`_ ...
`orQinln~AL
`supplem;n~ory
`orolnlne
`
`fumarate
`
`Figure 1. The Urea Cycle and Alternative Pathways of Waste Nitrogen Excretion.
`Complete deficiencies in carbamyl phosphate synthetase (CPS), ornithine transcarba(cid:173)
`mylase (OTC), argininosuccinate synthetase (AS), and argininosuccinase (AL) lead to
`decreased urea synthesis and neonatal hyperammonemic coma. Long-term therapy
`relies on nitrogen restriction and stimulation of alternative pathways of waste nitrogen
`excretion. Arginine supplementation stimulates the synthesis and excretion of citrulline
`in citrullinemia (AS deficiency) and of argininosuccinate in argininosuccinic aciduria
`(AL deficiency). In CPS and OTC deficiencies, sodium benzoate acylates glycine to
`form hippurate, and sodium phenylacetate acetylates glutamine to form phenylacetyl(cid:173)
`glutamine. Both waste nitrogen products (shown as boxed compounds) are readily
`excreted in urine.
`
`with abnormalities in tone or posture and with persistence of primi(cid:173)
`tive reflexes. Seizure disorder was defined as n·cutn•nt seizure activ(cid:173)
`ity and abnormal ekctroencephalo~raphic findin~s in the pn·S<·nn·
`of normal plasma ammonium le\'els.
`
`Developmental Assessment
`
`I Q was determined using the li1llowin~ psychometric tests: Bay(cid:173)
`ley Scales of Infant Oevt•lopmcnt (G to 30 months), Stanf(Jrd-Binct
`Scales (30 to 54 months), and Wechsler Preschool and Primary
`Scale of Intelligence (54 to 74 months). Tcstin~ was pcrftll'lliCd at
`least six months after the neonatal hypcrammotwmic episode and
`
`CT studies of the brain wt·n· perf(mm·d
`without contrast t•nhanCt·nwnt. using either
`a Si<·nH·ns Somatom DR3 or an :\S & E
`Pfizt•r 500 scanner, in ll patients ,.,·aluated
`at Johns Hopkins Hospital: one with defi(cid:173)
`cient carbamyl phosphate svntht·tase, f(lllr
`with deficient ornithine transcarbantvlast•,
`three with deficient ar~ininosuccinat<: syn(cid:173)
`tlwtasc.·, anrl three with deficient arg-inino~
`succinase. Scans were performed wht•n pa(cid:173)
`til'nts W<'l't.' between 6 \'I.Teks and 74 tnonths
`of a~l' (mean ±S.D., 18±20 motllhs) and
`were clinically stable.
`CT scans of the hrain were rated on the
`protninence of cortical sulci, \'entricular di-
`, latation, and brain .. substance lucency (Ta(cid:173)
`hk 2). The scorin~ system ran~ed from 0
`(normal) to 9 (severe vt•ntriculonw~alv with
`white-matter and cortical abnormalities).
`Ratin~s were done by two nt•uroradiologists
`who were unaware oftht• child's dinical his(cid:173)
`tor\'. The reliabilitv index lwtween the m·ur(cid:173)
`on{diolo~ists was 8.2 per cent. IQ testin~ was
`perf(Jrnwd within 6 months of the CT scan
`so that till' IQ and CT ratin~ could he <'lliT<'(cid:173)
`lated.
`Fi~ure:! consists oftht·t·e scans illustratin~
`the spectrum of abnormalities. St·an A is
`fi·mn a :H-month-old boy with ornithine
`transcarbarnylase deficiency. He was in
`Sta~e Ill neonatal hyperammom·mic coma l<1r three days, with a
`peak ammonium level of ·f:10 I!M. His IQ was 77 at 24 months of
`a~e. Ncurodt·\·t'lopnwntal examination l'l'\'ealt•d an attt•ntion-ddicit
`disorder with hyperacti,·ity. There was mild ,·,·ntricular dilatation
`on the CT scan obtained at 24 months of a~e; till' CT rat in~ was I.
`Scan B is fi·mn a 51-month-old boy with ar~ininosuccinase dl'licien(cid:173)
`cy who was in Sta~e Ill neonatal hyperammonemic coma f(n· three
`days, with a peak ammonium levd of 1280 1!111. His IQ was 55 at II
`months ofa~e. The child had microcephaly. ACT scan obtained at
`six months of a~e revealed a small increase in vt·ntricular size and
`patchy areas of parenchymal low dt·nsity; the CT ratin~ was 2.5.
`S<:an C is from a 19-month-old ar~ininosuccinaSt·-dl'licient patient
`who was in neonatal hyperantntntH'ntic
`coma with increased intracranial pressure
`for S<'Ven days, with a peak ammonium levd
`of600 ~Ill!. She was prof(lllndly mentally re(cid:173)
`tarded, with an IQ of 10 when tested at 14
`months of a~e. Development remaint'd at a
`newborn level. Slw also had ct·rd1ral palsy,
`mil'roccphaly, blindness, and a seizure dis(cid:173)
`order. Then· wen· no ret·urrent episodes of
`hyperammonemic coma. At 14 months of
`a~e the CT scan shO\\'l'd vcntriculmne~aly.
`prominent sulci. and subcortical low-density
`areas and was rated 5.
`Statistical Methods
`
`Table 1. Regimen for Long-Term Treatment of Patients with Inborn Errors of
`Urea Synthesis.•
`
`DlWICIENT
`ENZYME
`
`NATURAl.
`PROTl~IN
`
`ESSl!N'fiAl.
`AMINO ACIDS t
`
`CITRULLINE
`
`ARGININE'
`
`SOlliUM
`BENZOAH :f:
`
`8fWil$ per kilo~mm pt•r tltly
`
`CPS
`OTC
`AS
`AL
`
`0.6
`0.6
`1.2-1.5
`1.2-1.5
`
`0.6
`0.6
`
`0.1~
`0.18
`
`0.15
`0.25
`0.25
`
`0.4-0.7
`0.4-0.7
`
`SuUIUM
`Plti\N'I'I.ACEIATE §
`
`0.25
`0.25
`0.25
`
`•Calories supplemented with Mead Johnson Product 80056, to provide 120 kcal per kih1gram of hody weight ~r day. CPS
`denotes carbamyl phosplmtc synthetase, OTC omithinc trunM:arba1nylasc, AS argininosuccinatc _.,ynthct;~_.,c, und Al, argininn·
`succinuse.
`+Fohuc (0.1 to 0 . .5 mg per day) and pyridoxine (5 mg per day) were given with _.,odium bcnw<~tc.
`tContuins the following essential amino acids (g/kg/day):
`L-hiMidinc
`0.04
`t-isnlcm:inc
`0.07
`L·lcucinc
`0.13
`0.1 t
`L-lysinc
`
`1.-mcthilminc
`I.-phenylalanine
`t·thrconinc
`t.-tryptophan
`L·valine
`
`O.OJ
`0.07
`O.ll6
`0.03
`O.tl6
`
`§S"Klium phcnylacct<IIC was intrdduccd in 19K2.
`
`In addition to Student's t-tt•st and chi(cid:173)
`square analyst·s, the l(lllowin~ polynomial
`n·~n·ssion analyses were t·alculated: (I) du(cid:173)
`ration or CO Ill a \'t.'l'S\IS IQ at
`l ~ HHHlths.
`(:!) CT-scan ratin~ versus concurrent lQ.
`(:l) CT-st·an ratin~ \'l'l''lts duration ofhypl'l'(cid:173)
`ammmtemic coma, ( 4·) peak anunonium le\Tl
`versus lQ at I:! months. and (:1) peak ammo-
`
`The New England Journal of Medicine
`Downloaded from nejm.org by RHEANNA HAFNER on June 29, 2018. For personal use only. No other uses without permission.
`From the NEJM Archive. Copyright© 2010 Massachusetts Medical Society. All rights reserved.
`
`Par Pharmaceutical, Inc. Ex. 1008
`Par v. Horizon, IPR of Patent No. 9,561,197
`Page 2 of 6
`
`

`

`1502
`
`THE NEW ENGLAND .JOURNAL OF MEDICINE
`
`.June 7, I ~IB1
`
`Table 2. Rating Scales for Cerebral Abnormalities Demonstrated
`by CT Scan.
`
`Cortical sulci
`
`Ventricles
`
`Brain substance
`
`0 ~ normal
`I minimally prominent
`2 ~ moderately prominent
`3 = markedly prominent
`
`0 = normal
`I minimally dilated
`2 ~ moderately dilated
`3 markedly dilated
`
`normal
`0
`I ~ subcortical low density
`scanercd areas of low density
`2
`3 = confluent areas of low density
`
`nium level versus CT-scan ratin!(. The peak ammonium lt·vd was
`defined as the highest recorded plasma ammonium level durin.~
`neonatal coma; peak values in the patients have been reported pre(cid:173)
`viously.~ Excluded from these analyses (other than CT versus con(cid:173)
`current IQ) were two patients who were in a conta f(n· I~ and
`30 days.
`In addition, a paired l-test was used to determine the significanct·
`of changes in IQ from 12 months to f(>llow-up at 19 to H months.
`Excluded from this analysis were the f(,ur childn·n younger than Ill
`months. Also excluded was a child who had an episode ofhyperam(cid:173)
`rnonemic coma at 12 months, associated with Stage IV coma and
`increased intracranial pressure. This child's IQ fell from 7B to 10
`and was deemed outside the range we were considering clinically.
`This study was performed between 197B and 19B2 and involved a
`collaborative effort among 26 medical institutions in the United
`States and Europe. Parental consent was obtained, and the study
`was approvt:d by the Joint Conunittt·t· on Clinical Investigation at
`Johns Hopkins Hospital and by the institutional review hoards of
`participating hospitals.
`
`RESULTS
`
`Mortality
`Six of26 patients died during the study. Two male
`infants with ornithine transcarbamylase deficiency
`
`died before one year of age and arc not included in this
`paper. Four additional patients who have since died
`are included: one deficient in carbamyl phosphate
`synthetase, one in ornithine transcarbamylase, one in
`argininosuccinate synthetase, and one in argininosuc(cid:173)
`cinase. Two of the deaths resulted from intercurrent
`hypcrammonemic coma, one occurred after an acci(cid:173)
`dental I 0-fi:)ld overdose of intravenous sodium benzo(cid:173)
`ate and sodium phenylacetate during an episode of
`hyperammonemia, and one resulted from aspiration
`pneumonia. Postmortem examinations were not per(cid:173)
`mitted in any of these children.
`
`Neurologic Function
`Table 3 shows that of the 24 children, 19 (79 per
`cent) had one or more developmental disabilities: 46
`per cent had cerebral palsy, 79 per cent were mentally
`retarded, 17 per cent had seizure disorders, 54 per cent
`had microcephaly, and one child was blind; 46 per
`cent had more than one handicapping condition. The
`most recent IQ was 43±6 (mean ±S.E.M.). Twenty(cid:173)
`one per cent (five) of the children had an IQ above 70;
`broken down by type of deficiency, the percentages of
`children with an IQ above 70 were as follows: carba(cid:173)
`myl phosphate synthetase, 0 per cent; ornithine trans(cid:173)
`carbamylase, 60 per cent; argininosuccinate synthe(cid:173)
`tase, 12 per cent; and argininosuccinase, 12 per cent.
`Four of these five children had an attention-deficit
`disorder. A paired t-test was performed on the change
`between IQ at 12 months and the most recent IQ
`(mean, 35±4 months; range, 19 to 74) in 19 children.
`The IQ decreased by 8.6±2.5 points (P<O.OI) during
`this period.
`Figure 3 shows the relation between duration of
`Stage III or IV neonatal hypcrammonemic coma and
`
`Figure 2. CT Scans in Three Children with Complete Urea-Cycle Enzyme Deficiencies.
`Scan A shows mildly dilated ventricles (CT rating, 1.0) in a 24-month-old child with a deficiency of ornithine transcarbamylase. Scan B
`shows mild ventriculomegaly and patchy areas of parenchymal low density (CT rating, 2.5) in a six-monih-old infant with argininosuccin(cid:173)
`ase deficiency. Scan C shows ventriculomegaly, prominent sulci, and subcortical low-density areas (CT rating, 5.0) in a 14-month-old
`child with argininosuccinase deficiency.
`The New England Journal of Medicine
`Downloaded from nejm.org by RHEANNA HAFNER on June 29, 2018. For personal use only. No other uses without permission.
`From the NEJM Archive. Copyright© 2010 Massachusetts Medical Society. All rights reserved.
`
`Par Pharmaceutical, Inc. Ex. 1008
`Par v. Horizon, IPR of Patent No. 9,561,197
`Page 3 of 6
`
`

`

`Vol. 310 No. 23
`
`INBORN ERRORS OF UREA SYNTHESIS MSALL ET AL.
`
`1503
`
`Table 3. IQ and Developmental Disabilities in 24 One·Yee.r Survi·
`vors of Neonatal Hyperammonemic Coma.
`
`DEFICIENT No. OF
`ENZYME • PATIENTS
`
`AGE
`(Mo)
`
`DURATION OF
`COMA (DAYS)
`
`IQ AT
`12 Mo
`
`MOST
`DEVELOPMENTAL
`RECENT 01SABILITES (%) t
`
`tnt'Clll ::!::S.E.M.
`
`19:!:5
`21±4
`30:!:4
`41:!:7
`31±3
`12-74
`
`8
`8
`24
`
`12:!:9
`3±1
`5:!:1
`3±1
`5:!:1
`1-30
`
`58±24
`70± 12
`44±10
`50±7
`53±6
`10-100
`
`39± 15
`56±18
`37±10
`41±8
`43:!:6
`10-100
`
`CPS
`OTC
`AS
`AL
`Total
`Range
`•cps denotes carbamyl phosphate synthetase, OTC ornithine transcarbwnylasc. AS argini·
`nosuccinate synthetase, and AL argininosuccinasc.
`tDevelopmental findings for the group as a whole were as follows: nonnul function, 21 per
`cent; mental retardation. 79 per cent: cerebral palsy, 46 per cent; seizure disonler, 17 per cent:
`blindness, 4 per cent: microcephaly. 54 per cent; und multiple handicaps. 46 per cent.
`
`100
`40
`88
`88
`
`was also a significant linear correlation between du(cid:173)
`ration of coma and CT-scan rating (r = 0.85,
`Y = 0.98x- 0.97, P<O.Ol; Fig. 5). There was no sig(cid:173)
`nificant correlation between peak ammonium level
`during hyperammonemic coma and CT rating.
`
`DISCUSSION
`It was not previously possible to perform a long(cid:173)
`term follow-up study of patients with congenital urea(cid:173)
`cycle enzyme deficiencies, because of the poor one(cid:173)
`year survival rate. In 1976 Shih 1 reviewed the outcome
`in patients with complete urea-cycle enzyme deficien-
`
`IQ at 12 months of age. There was a significant nega(cid:173)
`llx + 95,
`tive linear correlation (r = -0.72, y =
`P<O.OO I); the longer the duration of coma, the
`more likely that the child would be mentally retarded.
`Four of the five children, whose duration of coma
`was two days or less had normal IQ scores at 12
`months, whereas all seven children whose duration of
`coma was f1ve days or more were mentally retarded.
`There was no signif1cant correlation between peak
`ammonium level (351 to 1800 ,uM) and IQ score at 12
`months.
`
`0 -c.
`
`Q)
`'-
`'-
`:::J u
`c.
`0 u
`
`•
`•
`
`Computed Tomography
`CT scans were performed in II children stud(cid:173)
`ied at the Johns Hopkins Hospital. Figure 4 shows
`the relation between CT rating and concurrent IQ
`score. There was a significant negative linear cor(cid:173)
`relation (r = -0.75, y = -9.8x + 76, P<0.02). There
`•
`
`o~~~~--._~~--~~~
`
`2 3 4 5 6 7 8 9
`CT Scan Score
`Figure 4. Relation between CT Abnormality Rating and Concur·
`rent IQ (r = -0.75, y = -9.8x + 76, P<0.02, n = 11 ) .
`
`(/)
`
`.c. .-
`c
`0
`2
`
`N -0
`
`e:!
`0 u
`(/)
`0
`
`• •
`•
`
`•
`
`•
`•
`
`•
`
`•
`
`Duration Coma in Days
`
`cies before the use of alternative-pathway therapy.
`Among 28 patients (5 deficient in carbamyl phosphate
`synthetase, 10 deficient in ornithine transcarbamy(cid:173)
`lasc, 6 deficient in argininosuccinatc synthetase, and 7
`deficient in argininosuccinase) the one-year survival
`rate was 14 per cent. Three of the four survivors were
`mentally retarded .
`In our study, there was a 92 per cent one-year sur(cid:173)
`vival rate among 26 patients with complete urea-cyde
`enzyme deficiencies treated with a combination
`of nitrogen restriction and supplements of sodium
`benzoate, arginine, citrulline, and more recently, so(cid:173)
`dium phenylacetate. Although survival improved,
`neonatal hyperammonemic coma had a devastating
`effect (Table 3). Seventy-nine per cent of our pa(cid:173)
`tients had at least one developmental disability, and
`46 per cent had multiple handicaps (some combina-
`·
`d
`-
`.
`Figure 3. Relation between Duration of Neonatal Hyperammone-
`1
`Uon of menta retar anon, cerebral palsy, and sei-
`mic Coma and 10 at 12 Months of Age (r = -0.72,
`y = -11x + 95, P<0.001, n = 22).
`zures) when evaluated at ages ranging from 12 to 74
`months.
`The triangles indicate two children who were in coma for 12 to 30
`Ammonia has been implicated as a neurotoxin in a
`days and are not included in the correlation.
`The New England Journal of Medicine
`Downloaded from nejm.org by RHEANNA HAFNER on June 29, 2018. For personal use only. No other uses without permission.
`From the NEJM Archive. Copyright© 2010 Massachusetts Medical Society. All rights reserved.
`
`Par Pharmaceutical, Inc. Ex. 1008
`Par v. Horizon, IPR of Patent No. 9,561,197
`Page 4 of 6
`
`

`

`1504
`
`9
`8
`
`~
`0 u
`(f) 5
`c::
`0
`u
`(f)
`I-
`u
`
`4
`3
`2
`
`0
`
`2 3 4 5 6 7
`Duration Coma in Days
`Figure 5. Relation between Duration of Neonatal Hyperammone(cid:173)
`mic Coma and CT Abnormality Rating (r = 0.85,
`y = 0.98x
`0.97, P<0.01, n = 10).
`The triangle indicates a child who was in coma for 30 days and is
`not included in the correlation.
`
`number of disorders, including portal-systemic en(cid:173)
`cephalopathy/ Reye's syndrome, 11 and un:a-cyck en(cid:173)
`zyme deficiencies. The pathophysiology of ammonia
`toxicity, although unclear, has been variously ascribed
`to increased permeability of' the blood-brain barrier,
`depletion or in termediatcs in energy metabolism, and
`a cytotoxic dkct on microtubular aggregates, causing
`disruption or cytoplasmic integrity.~' In animal mod(cid:173)
`els, hypcrammoncmia (ammonium levels above 1000
`~-tM) leads to reversible swelling of astrocytes and in(cid:173)
`creased intracranial pressurc. 10
`Survivors who are sevcrdy mentally retarded have
`chronic neuropathological findings, including in(cid:173)
`creased ventricular size, areas of f(Kal cortical necro(cid:173)
`sis, and frontal-parietal ulegyria. 11 - 1'' Myelination has
`been variously described as normal or deficient. These
`findings may reflect hypoxia, hypovolemia, and in(cid:173)
`creased intracranial pressure, as well as the precipitat(cid:173)
`ing hyperammonemia. Thus, the associations we
`f(Jund between duration or coma and brain damage
`may reflect all these factors. Jn f;tct, one of'our patients
`had a cardiopulmonary arr<~st, and a number had res(cid:173)
`piratory distress or increased intracranial pressure or
`both during neonatal hyperammonemic coma.
`CT findings in patients with urea-cycle disorders
`have been consistent with the neuropathological find(cid:173)
`ings. Kendall et al. I!; noted cerebral atrophy, ven(cid:173)
`triculomegaly, and low-density white matter in S<~ven
`mentally retarded patients with partial ornithine
`transcarbamylasc deficiency. We noted similar CT
`abnormalities in our patients with complete urea-cycle
`enzyme dekcts. We also f(JUnd a significant correla(cid:173)
`tion between CT abnormalities and duration of' neo(cid:173)
`natal hyperammonemic coma. Furthermore, the J Q
`
`THE NEW ENGLAND .JOURNAL OF MEDICINE
`
`.June 7, 19!l1
`
`scores at 12 months were directly correlated with the
`length or time in neonatal hyperammonemic coma. A
`good prognosis was observed in patients with coma
`lasting less than three clays. In this group, four of five
`children had a normal lQ. Conversely, patients in
`Stage II I or IV coma for more than five clays were
`invariably handicapped. The peak ammonium level
`(between 351 and 1800 ~-tM) was not correlated with
`JQ at 12 months. A multivariate analysis indicated
`that the peak ammonium level did not add to the sig(cid:173)
`nificance of the association between duration of coma
`and IQ at 12 months. However, with a sample size
`this small nonsignificant results should not be inter(cid:173)
`preted as indicating that the relation does not exist.
`Part of the cfkct of the small sample size is reflected in
`the relatively large variation indicated by the calculat(cid:173)
`ed standard error or the mean in Table 3. Despite the
`f~1ct that all these inf~mts had complete or nearly com(cid:173)
`plete enzyme deficiencies,~ the possibility remains that
`small variations in residual enzyme activity may have
`played a part in the ultimate outcome.
`A comparison between IQ at 12 months and at f(JI(cid:173)
`Iow-up (19 to 74 months) showed a mean decrease of
`B.G points. It is unclear whether this decline in IQ was
`clinically important, since it occurred in patients who
`wne already handicappccl. 17- 1 ~ 1 If' so, the decrease may
`have been attributable to one or more of the following
`fi1ctors: intercurrent hyperammonemic episodes, drug
`toxicity, toxicity of citrulline or argininosuccinic acid,
`or inadequate infant stimulation or nutrition.
`This study indicates an association between the du(cid:173)
`ration of Stage lJ I or IV neonatal hypcrammonemic
`coma and brain damage, as evidenced by abnormali(cid:173)
`ties on CT scan. The findings indicate a similar associ(cid:173)
`ation between duration of coma and future intellectual
`function. Theref(Jre, one might speculate that unless
`therapy is started during the earliest stages of hyper(cid:173)
`ammonemic coma in infants, most will be severely
`handicapped.
`
`\Ve an· indebted to <he f<>llowing physicians who collaborau·d in
`the treatllH'Ilt of the patients: Arthur Beaudet, Barbara Burton,
`Howard Cann, St<'V<'II Cederhaum, Mark Danney, Gerald Fen(cid:173)
`ch·ick, Richard Flaxman, .John J-lowich, Douglas Kerr, Lynn Le(cid:173)
`vitsky, Peter Mamuncs, Paul Marquis, Reuben Matalon, Virginia
`Michels, Catherine Mizc, David Myerherg, Michael Painter, .James
`C. Parke, Carla Pierce, Norman Rao, Robert Richardson, Irwin
`Schaf<-r, George Sproul, Rebecca \Vappncr, .Jewell \Van!, and \Vii·
`liam Yang; to A . .J. Kumar, S. B. Rosenbloom, and 1-1. Seagcll fc>r
`rating the CT scans; to Bernaditw l'ct<·rs and the stall' nurses of the
`Pediatric Clinical Research Unit; and to Rosemary Baumgardner
`Ji1r technical assistancl'.
`
`REI'ERENCES
`
`I. Shih VE. Hereditary urea-cycle disorders. In: Grisolia S. Baguena R, Mayor
`r, eds. The urea cycle. New York: John Wiley, 1976:367-414.
`2. Batshaw ML, Brusiluw SW. Wabcr L, ct al. Treatment of inborn errors of
`urea synthesis: activation of alternative pathways of waste nitrogen synthesis
`ami excretion. N Eng! J Mcd 1982; 306:1387-92.
`3. Brusilow SW, Bmshaw ML, Wabcr L. Neonatal hypcrammoncmic coma.
`Adv Pediatr 1982; 29:69-103.
`ljpma ST. Blijcnbcrg BG, Lcijnsc B. Evaluation of the DuPont am ammo(cid:173)
`nia procedure. Clin Chern 1'178; 24:489-92.
`5. Huncnlochcr PR. Reye's syndrome: relation of outcome to therapy. J Pe(cid:173)
`diatr 1972; 80:845-50.
`
`4.
`
`The New England Journal of Medicine
`Downloaded from nejm.org by RHEANNA HAFNER on June 29, 2018. For personal use only. No other uses without permission.
`From the NEJM Archive. Copyright© 2010 Massachusetts Medical Society. All rights reserved.
`
`Par Pharmaceutical, Inc. Ex. 1008
`Par v. Horizon, IPR of Patent No. 9,561,197
`Page 5 of 6
`
`

`

`Vol. :~10
`
`:'\o. :13
`
`EFFECT OF PREPAID GRot:!' I'R:\CTICE- :"\I.\:'\:'\ I:-\(; ET .\L.
`
`6. American Psychiatric Association. Diagnostic ami statistk·o.il manual of
`mental disorders. 3rd cd. Washington, D.C.: American Psychiatrk Associ~
`at ion, 1980:35-99.
`7. Zicvc L. The mechanism of hepatic coma. Hcpalology I 'lXI; 1:360-5.
`8. DeLong GR. Glick TH. Encephalopathy of Reye's syndrome: a review of
`pathogenetic hypotheses. Pediatrics 1982: 69:53-63.
`9. Flannery DB. Hsia YE. Wolf B. Current status of hyperammonemic syn(cid:173)
`dromes. Hcpatology 1982; 2:495-506.
`10. Voorhies TM. Ehrlich ME. Duffy TE. l'clilo CK, Plum F. Acute hypcram(cid:173)
`moncmia in the young primate: physiologic and ncurupathologit torrclutcs.
`Pedialr Res 1983; I 7:970-5.
`II. Leibowitz J, Thoene J, Spector E. Nyhan W. Citrullincmia. Virchows Arch
`!'athol Anal 1'178; 377:249-58.
`12. Martin JJ, Farriaux Jl'. De Jonghc 1'. Neuropathology of cilrullinacmia.
`A<'la Neuropathol (Bcrl) 1982; 56:303-6.
`13. Ebcls EJ. Neuropathological observations in a patient with carbamyl phos(cid:173)
`phatc-synthcwsc dclicicncy and in two sibs. Arch Dis Child 1972: 47:47-51.
`
`14. Bruton CJ. Corsdlis JAN. Russell A. Hereditary hypcranunonemia. Brain
`1970; 93:423-33.
`15. Solitare GB. Shih VE, Nelligan DJ. Dolan TF Jr. ArgininosU<'dnk aciduria:
`~..·Iinical. bi(lChL·mical.
`;.mattlmical omd ncuropath~lhlgical ob:-;cn·•ni~ms.
`J Ment Dclk Res 1%9: 13:153-170.
`16. Kendall BE. Kinpky DPE. Leonard JV. Lingam S. Obcrhol1.er VG. Ncu(cid:173)
`rnlogical r~aturcs and ~omputed tomography of the brain in l'hildrcn with
`omithinc carbamoyl transferase Uclicicn~.:y. J Neurol Neurosurg Psy<..'hi:Hry
`1983; 46:28-34.
`17. Hindley CB, Owen CF. The extent of individual changes in l.Q. for ages
`between (1 months and 17 years, in a British longitudinal sample. J Child
`Psycho! l'sychi"try 197H: 19:32'1-50.
`18. VanderVeer B. Schweid E. Infant assessment: stabilitv of mental hliH.:tion(cid:173)
`ing in young retarded children. Am J Mcnt Dclil' l'J'l4: 79:1-4.
`1'1. Fishier K, Gralik<'r BY. Koch R. The predictability uf intclligetK'C with
`Gesell Developmental Scales in m~ntally rctan.kd infants and young chil(cid:173)
`dren. Am J Ment Dclil- 1965: !1'1:515-25.
`
`SPECIAL ARTICLE
`
`A CONTROLLED TRIAL OF THE EFFECT OF A PREPAID GROUP PRACTICE
`ON USE OF SERVICES
`
`WILLARD G. MANNING, Pu.D., ARLEEN LEmowrrz, Pu.D., GEoRm: A. GOI.DBERG, l\LD.,
`VVII.I.IAM H. RoGERs, Pn.D., AND JosEPH P. NEWI!ot'SE, PH.D.
`
`Abstract Does a prepaid group practice deliver less
`care than the fee-for-service system when both serve
`comparable populations with comparable benefits? To an(cid:173)
`swer this question, we randomly assigned a group of 1580
`persons to receive care free of charge from either a fee(cid:173)
`for-service physician of their choice (431 persons) or the
`Group Health Cooperative of Puget Sound (1149 per(cid:173)
`sons). In addition, 733 prior enrollees of the Cooperative
`were studied as a control group.
`The rate of hospital admissions in both groups at the
`Cooperative was about 40 per cent less than in the fee-for(cid:173)
`service group (P<0.01 ), although ambulatory-visit rates
`were similar. The calculated expenditure rate for all serv-
`
`ices was about 25 per cent less in the two Cooperative
`groups (P<0.01 for the experimental group, P<0.05 for
`the control group). The number of preventive visits was
`higher in the prepaid groups, but this difference does not
`explain the reduced hospitalization. The similarity of use
`between the two prepaid groups suggests that the mix of
`health risks at the Cooperative was similar to that in the
`fee-for-service system. The lower rate of use that we ob(cid:173)
`served, along with comparable reductions found in non(cid:173)
`controlled studies by others, suggests that the style of
`medicine at prepaid group practices is markedly less "hos(cid:173)
`pital-intensive" and, consequently, less expensive.
`(N Engl J Med 1984; 310:1505-10.)
`
`H EALTH_ -maintenance organizations ( H l'vl Os)
`
`have been advocated for many years as an im(cid:173)
`portant innovation in medical-care delivery; indeed,
`for a decade, federal leg-islation and subsidies have
`encouraged their f(mnation. Previous studies played a
`large part in persuading the Congress and the execu(cid:173)
`tive branch to promote enrollment in HMOs. They
`indicated that the prepaid-group-practice variant of'
`HMOs has ambulatory-visit rates similar to those in
`fee-for-service medicine but has hospital-admission
`rates that are as much as 40