Evaluation of Internists' Spirometric Interpretations MAJ Oleh Hnafiuk, MAJ Lisa Moores, MAJ Thomas Loughney, COL Kenneth Torrington

BACKGROUND: Correc t i n t e r p r e t a t i o n of s c r een ing sp i rome- t ry r e su l t s is e ssen t i a l in m a k i n g accura te c l inical d iagnoses and d i rec t ing s u b s e q u e n t p u l m o n a r y eva lua t ion . The genera l i n t e r n i s t is largely respons ib le for i n t e r p r e t i n g sc reen ing sp i rome t r i c t e s t s a t c o m m u n i t y hospi ta ls . However, r epo r t s of new guidel ines for s c reen ing s p i r o m e t r y are in f r equen t ly pub l i shed in t h e genera l i n t e rna l m e d i c i n e l i t e ra tu re . This can lead to i nco r r ec t i n t e r p r e t a t i ons . We s o u g h t to eva lua te w h e t h e r sp i rome t r i c i n t e r p r e t a t i o n s by a group of p rac t i c ing genera l i n t e r n i s t s differed f rom those of two board-cer t i f ied pu lmonolog i s t s us ing guide l ines pub l i shed by t h e Amer i can Thorac ic Soc ie ty (/ITS).

METHODS: As pa r t of a C o n t i n u o u s Qual i ty I m p r o v e m e n t project, all available screening spirometr ic t e s t s over a 3 -month per iod a t two a rea c o m m u n i t y hosp i t a l s were reviewed. Only t h o s e pe r fo rmed on ind iv idua ls age 18 or o lder were inc luded in t h e analysis . Compar i son was made be t w een t h e in te rp re - t a t i o n s of s ta f f i n t e r n i s t s and t h o s e of two pn lmonolog ls t s , who were b l inded to t he r e su l t s of all o t h e r i n t e rp re t a t i ons . We ana lyzed 110 sc reen ing sp i rome t r i c t e s t s f rom 84 males and 26 females. The p a t i e n t s ranged in age f rom 18 to 77 (mean 41 +_ 13 years of age).

RESULTS: There was 97% conco r dance be t w een t he two pul- mono log i s t s ' i n t e rp re t a t i ons . In t h r e e cases, i n t e r p r e t a t i o n s of only one pn lmonolog i s t agreed wi th t hose of t he in ter - n is t s . The i n t e r n i s t s and b o t h pu lmonolog i s t s agreed in 73 cases, The ma jo r i ty of sp i rome t r i c r e su l t s in t h i s subgroup were n o r m a l (n = 54). Bo th pu lmonolog i s t s d isagreed w i th in- t e r n i s t s ' n o m e n c l a t u r e in five cases. There was comple te dis- a g r e e m e n t be tween t h e pu lmonolog i s t s a n d t h e i n t e r n i s t s in t he o t h e r 29 cases, Using t he pu lmonolog i s t s ' i n t e r p r e t a t i o n s as t h e "gold s t anda rd , " t h e s ens i t i v i t y ( the in te rn is t s" abi l i ty to cor rec t ly iden t i fy abno rma l sp i rome t r i c resul ts) was 58.8% (95% conf idence in te rva l [CI] 42.2%, 73.3%), t h e spec i f ic i ty was 81 .8% (950/0 CI 70,00/0, 89.8%), t he pos i t ive p red ic t ive va lue was 66 .7% (95% CI 49.0%, 80.9%), and t h e nega t ive pred ic t ive va lue was 76 .1% (95% CI 64.3%, 85.00/0). The m o s t c o m m o n inaccu ra t e i n t e r p r e t a t i o n s made by i n t e r n i s t s were "smal l airways d isease" when sp i romet r i c r e su l t s were nor- mal (n = 8); "normal" w h e n a r e s t r i c t ive p a t t e r n was p r e s e n t (n = 6), and "normal" w h e n a n abno rma l f low-volume loop sugges t ing possible upper airway obs t r uc t i on was p r e s e n t ( n : 5) .

CONCLUSIONS: The sp i rome t r i c i n t e r p r e t a t i o n s of a group of genera l i n t e r n i s t s differed s igni f icant ly f rom t h o s e of two board-cer t i f ied pu lmonolog i s t s us ing pub l i shed guide l ines in approx imate ly one t h i r d of cases. This m a y be because sub- spec ia l ty guide l ines are in f requen t ly pub l i shed in t he genera l i n t e r n a l med ic ine l i t e ra ture . We bel ieve t h a t wider d issemi- n a t i o n of t h e s e i n t e r p r e t a t i ve guide l ines and ongoing physi- c i an educa t i on would Improve genera l i n t e r n i s t s ' abi l i ty to iden t i fy p a t i e n t s who requi re fu r the r p u l m o n a r y evalu- a t ion .

204

K E Y WORDS: p111monary funct ion tes ts ; spirometry; guide- l ines. J GEN INTERN MED 1 9 9 6 ; 1 1 : 2 0 4 - 2 0 8 .

S c r e e n i n g s p i r o m e t r y h a s a w ide r a n g e of a p p l i c a t i o n s .

In n o n t e a c h i n g a n d c o m m u n i t y h o s p i t a l s , i t is o f t en

g e n e r a l internists, r a t h e r t h a n p u l m o n o l o g i s t s , w h o i n t e r -

p r e t t h e r e s u l t s of s c r e e n i n g s p i r o m e t r y . T h i s i n f o r m a t i o n

is u s e d to deve lop d i f f e ren t i a l d i a g n o s e s , follow t h e c o u r s e

of d i s e a s e s , e v a l u a t e r e s p o n s e s to t h e r a p y , a n d a s s e s s t h e

e x t e n t of p e r i o p e r a t i v e r i s k for p u l m o n a r y c o m p l i c a t i o n s .

T h e N a t i o n a l A s t h m a E d u c a t i o n P r o g r a m s t a t e s t h a t

s p i r o m e t r y is e s s e n t i a l i n t h e d i a g n o s i s a n d m a n a g e m e n t

of a s t h m a b e c a u s e of e v i d e n c e t h a t b o t h p a t i e n t s a n d

p h y s i c i a n s h a v e i n a c c u r a t e p e r c e p t i o n s of t h e s eve r i t y of

a s t h m a t h a t c o n t r i b u t e to d e l a y s in t r e a t m e n t , U n d e r e s t i -

m a t i o n of t h e e x t e n t of a iHlow o b s t r u c t i o n h a s b e e n a s s o -

c i a t e d w i t h i n c r e a s e d m o r b i d i t y a n d m o r t a l i t y in p a t i e n t s

w i t h a s t h m a . ~ S p i r o m e t r y i s o f t en u s e f u l w h e n t h e r e m a y

b e m o r e t h a n one e x p l a n a t i o n for t h e p a t i e n t ' s s y m p t o m s .

As a n e x a m p l e , a s m o k e r w i t h d y s p n e a a n d k n o w n

c h r o n i c conges t i ve h e a r t f a i lu re m a y a l so h a v e c h r o n i c

o b s t r u c t i v e p u l m o n a r y d i s e a s e (COPE)). T h e f a i l u re to rec-

ogn ize a n d t r e a t b o t h d i s o r d e r s m a y l imi t t h e u l t i m a t e

t h e r a p e u t i c r e s p o n s e . A c c u r a t e s p i r o m e t r i c i n t e r p r e t a -

t i ons a re e s s e n t i a l in m a k i n g t imely a n d effective dec i s ions .

S t u d i e s e v a l u a t i n g t h e c o n c o r d a n c e r a t e s b e t w e e n

p r i m a r y ca r e p h y s i c i a n s ' a n d ca rd io log i s t s ' i n t e r p r e t a -

t i o n s of e l e c t r o c a r d i o g r a m s (ECGs) 2. a a n d h e m o d y n a m i c

d a t a 4 h a v e r e c e n t l y a p p e a r e d in t h e l i t e r a tu r e , T h i s s t u d y

w a s d e s i g n e d to d e t e r m i n e w h e t h e r s i m i l a r d i s c o r d a n c e

e x i s t s in t h e a r e a of s c r e e n i n g s p i r o m e t r y . To o u r knowl -

edge, t h i s is t h e f i r s t s t u d y to e v a l u a t e s p i r o m e t r i c i n t e r -

p r e t a t i o n s b y g e n e r a l i n t e r n i s t s . By d o c u m e n t i n g a n d de-

From the Pulmonary and Critical Care Medicine Service, Walter Reed Army Medical Center, Washington, DC, and the Depart- ments of Medicine, Dewitt Army Community Hospital, Fort Bel- voir, Virginia, and Kimbrough Army Community Hospital, Fort

Meade, Maryland. Presented in part at the annual meeting of the American Col-

lege of Physicians, U.S. Army Region, Orlando, Florida, Novem- ber 20, 1993.

The opinions contained herein represent solely the views of the authors and are not to be construed as representing the views of the Department of Defense or the Department of the

Army. Address correspondence and reprint requests to MAJ Hna-

tiuk: Director, Pulmonary. Diagnostic Services, Pulmonary and Critical Care Medicine Service, Washington. DC 20307-5001.

JGIM Volume 11, April 1996 205

scribing existing inaccuracies, we hope to raise physician

awareness of this problem and improve the accuracy and

clinical utility of spirometric interpretations. This should resul t in better identification of pat ients who require fur- ther subspecial ty evaluation by a pulmonologist.

METHODS

As part of a Walter Reed Army Medical Center Contin- uous Quality Improvement project, all available screening spirometric tests performed on pat ients older t han 18, be- tween J a n u a r y 1 and March 31, 1993, at Dewitt A ~ y

Communi ty Hospital (DACH) and Kimbrough Army Com-

muni ty Hospital (KACH), were collected. Spirometrie data associated with full pu lmonary funct ion tests were ex-

cluded. The spirometric data were separated from the original interpretat ion sheets and reinterpreted by two pulmonologists, who were bl inded to the resul ts of all other original interpretat ions.

Interpretat ions by the pulmonologists were made us-

ing values for forced expiratory flows obtained from the ef- fort with the largest s u m of forced vital capacity (FVC} p lus forced expiratory volume in one second (FEVI). Lower limits of normal for the FVC and the ratio of FEV I to FVC

(FEVI/FVC) were determined us ing 95% confidence inter- vals (CI) established by Morris and associates. 5 The sever-

ity of abnormali t ies was determined us ing the FEVI per- centage predicted, according to the example proposed by the American Thoracic Society (AT"S).6 In addition, the fol-

lowing categories were added ~mixed pattern" with defi- nite mild, moderate, and severe obstructive ventllatory

defects and "possible upper airway obstruction." An inter- pretat ion of "mixed pattern" was rendered when both FVC and FEV1/FVC were outside the 95°/o CI. The degree of se-

verity of obstruct ion was graded by the percentage pre- dicted of normal of the FEVp An interpretat ion of "possi-

ble upper airway obstruction" was rendered ff there was flattening of either the inspiratory or expiratory flow-

volume loops and ratio of FEVI to peak expiratory flow

rate > 0 .6 /second, or ratio of 50% forced expiratory flow to 50% forced inspiratory flow (FEFs0o/0/FIFso%) > 1, or FIF50% < 1.7 L/second, or ratio of FEV1 to forced expira- tory volume in 0.5 second (FEV1/FEVo,5) > 1.5. 6

During the s tudy period, spirometry at both hospitals was performed us ing a heated pneumotachograph (at KACH, CAD/NET System 1070, MedGraphics Inc., St. Paul, MN; at DACH, Multispiro-PC, Medical Equipment

Designs, Laguna, CA). Testing followed publ ished guide- lines for performance of pu lmonary funct ion tests. 7-11 All

tests were conducted on pat ients seated in the upright

position. The original interpretat ions rendered by the inter-

n is ts and the pulmonologists ' reinterpretat ions were then combined and compared. Data were analyzed us ing SPSS 5.0 for Windows software. A two-by-two table was con-

structed, and interrater agreement was assessed us ing Cohen's K statistic and McNemar's test for matched pro-

portions. For most purposes, K values greater t han 0.75 may be taken to represent excellent agreement beyond

chance, values below 0.40 or so may be taken to repre- sent poor agreement beyond chance, and values between 0.40 and 0.75 may be taken to represent fair to good agreement beyond chance. All statistical tests are two-

sided, with p < .05 considered significant.

RESULTS

We analyzed 110 spirometric tests performed on 84 males and 26 females. The group consisted of 88 white,

17 African-American, 3 Asian, and 2 Hispanic subjects with a mean age of 41 years (_+ 13 years), ranging from 18

to 77 years of age, Fifty-eight spirometric tests were per- formed at KACH, and 52 at DACH. Spirometry results in this group, as interpreted by both pulmonologists, re-

vealed 66 normal studies, 22 obstructive ventilatory de- fects, 12 restrictive pat terns, 2 mixed defects, and 5 with possible upper airway obstruction. In three cases, one of

the pulmonologists disagreed with interpretat ions of the other pulmonologist and internists , and in each of these

three cases (two normal s tudies and one moderate ob- structive ventilatory defect], the inspiratory flow-volume curve was interpreted as abnormal by the dissent ing pup

monologist. All three cases were excluded from further

analysis. The two pulmonologists participating in the s tudy

were military-trained, board-certified pulmonologists

who had worked in academic Army teaching hospitals, one for the past 3 years, and the other for more t han 12 years. Both pulmonologists followed ATS guidelines for

the interpretation. 6 Seven board-certified general inter- n is ts read the spirometric tests at DACH. All were Army-

trained, and experience ranged from 1 to 12 years. One internis t was also a board-certified gastroenterologist. At KACH, seven board-certified internis ts interpreted spiro-

metric results. Three of these were Army-trained physi- c ians with 1 to 3 years of experience. The other four were

civilian-trained with an average of 5 years ' experience. Neither communi ty hospital was us ing a s tandardized al- gorithm for the interpretat ion of spirometry, with each in-

dividual in ternis t bas ing his or her assessment on past

experience and training. There was full agreement between the in ternis ts and

both pulmonologists in 73 cases. The majority of these cases (n = 54) showed normal spirometry. In 34 cases

both pulmonologists disagreed with the internists . Spiro-

metric resul ts were normal, b u t interpreted as abnormal by the internis ts in 12 of the 34 cases. In another 12

cases, the in ternis ts interpreted the spirometric resul ts as normal when an abnormal i ty was identified by the pulmo- nologists (Table i}. In the remaining 10 cases the spiro- metric results were interpreted as abnormal by both the pulmonologists and the internists . Disagreement in inter-

pretat ional nomencla ture accounted for five of these cases. In three of these five cases, the word "COPD" ap-

206 H n a t i u k e t at., In ternis ts" Sp irometr ic In t e rpre ta t ions IGIM

peared in place of the more generic "defect" (i.e., "mild

COPD" instead of "mild obstructive ventilatory defect").

Table 2 displays the two-by-two comparison of the con- cordance between interpretat ions of in ternis ts and pul- monologists. The K statistic is 0.41, which reflects poor agreement beyond chance.

Using the interpretat ion of the pulmonologists as the "gold standard," the internis ts correctly identified normal

spirometry in 54 of 66 cases (specificity = 81.8%; 95% CI 70.0%, 89.8% ), and correctly identified abnormal spirom-

etry in 24 of 41 cases (sensitivity = 58.8%, 95% CI 42.2%, 73.3% ). Similarly, of the 71 cases tha t the in ternis ts judged as normal, 54 were declared normal by the pulmo-

nologists (negative predictive value 76.1%, 95% CI 64.3%,

85.1%). Of the 36 spirometric tests read as abnormal by the internists , the pulmonologists declared 24 as abnor-

mal (positive predictive value 66.7%, 95% CI 49°/6, 80.9%). Inaccurate interpretat ions were made by 10 of the 14

general in tern is ts (Table 3). Members of this group had graduated from both cimlian and military internal medi-

cine t ra ining programs 1 to 9 years previously. Four indi- viduals were responsible for 25 of the 34 inaccurate inter-

pretations. Of the 34 inaccurate interpretations, 25 were from one of the two Army communi ty hospitals.

DISCUSSION

With the current emphasis on a greater role for the pr imary care physician, the quest ions of when and where these physicians can perform the roles traditionally as- signed to subspecialists become paramount . General in-

ternists are often performing and interpret ing rout ine lab-

oratory tests, ECGs, and screening spirometry in office or communi ty hospital settings. Although this saves time and increases convenience for both pat ient and physi- cian, the accurate interpretat ion of these tests is essential to ma in ta in an appropriate s tandard of care. Recent s tud-

ies in the medical l i terature have raised the quest ion of

the overall accuracy of internis ts ' interpretat ions of s tan- dard 12-lead ECGs when compared with those of cardiol- ogists. McCrea and Saltissi reported that in a prospective

Table I. Spirometric Interpretations by Internists

Normal results interpreted as abnormal (n = 12} Small airways diseases 8 Mild obstructive lung disease 1 Moderate COPD/mild restriction 1 Moderate/severe obstructive and restrictive

lung disease 1 Mild restriction 1

Abnormal results interpreted as normal (n = 12) Abnormal flow-volume loops consistent with possible

upper airway obstruction 5 Mild restrictive patterns 5 Moderate restrictive pattern 1 Mild obstructive ventilatory defect 1

Table 2. Agreement between Observers*

Both Pulmonologists Normal Abnormal

Internists Spirometry Spirometry

Normal spirometry 54 17 Abnormal spirometry 12 24 t

*Sensitivity, 58.896 (95% CI 42.2%, 73.3%); specificity, 81.8% (95% CI 70.0%, 89.8%); posit ive predict ive value. 66.7% (95% CI 49.0%, 80.9%); negative predict ive value, 76.1% (95% CI 64.3%, 73.3%); K = 0.41; McNemar )(2 - 0.55, p = .46. *Inctudes the f i ve abnormal spirometric resul ts in which the only d i sagreemen t s were in nomenclature.

s tudy of 106 pr imary care physicians, 82% could accu- rately identify a normal ECG. 3 However, only 33% to 61% could identify acute t r ansmura l ischemia or infarction,

depending on the specific tracing presented. They con- cluded that their r andom sampling of practi t ioners re-

vealed that refresher t raining is needed if general practi- t ioners are to recognize acute infarctions and adminis ter timely thrombolytic therapy. Westdorp and colleagues ret-

rospectively reviewed all abnormal ECGs for pat ients dis- charged from a Level 1 T rauma Center emergency depart- men t and compared the concordance rates between the emergency depar tment physician 's and the cardiologist's interpretations. 2 Although the overall discordance rate

was more than 50°/6, most emergency depar tment misin- terpretat ions were determined unlikely to have clinical

significance. The s tudy used the clinical gold s tandard, which was the final computer-read, cardiologist-overread

interpretat ion of the ECG. The authors acknowledged that this clinical gold s tandard may not always reflect the ac- tual correct ECG interpretation, which is determined by

interpretat ional concordance among at least two cardiolo-

gists. Test quality remains the most important concern in

lung function testing. Variability may be greater in pul- monary funct ion testing than in many other clinical tests

owing to the dependence on pat ient effort. The elements

that lead to a high-quali ty test are accurate equipment, good pat ient cooperation and effort, cont inuing quality

assessment , appropriate reference values, and a s t andard algorithm for the interpretat ion of results. In 1991, the ATS published guidelines for reference values and inter- pretation of lung function testing in a medical subspe-

cialty journal . 6 The guidelines contain important new rec-

ommendat ions for spirometric interpretation.

1. "Normal ranges should be calculated based on cal- culat ion of fifth percentiles," not 80% predicted.

2. "It is not acceptable to use a Fixed FEV~/FVC ratio

as a lower limit of normal". 3. "FEF25._75 and the i n s t an t aneous flows should not

be used to diagnose small airways disease in indi-

IGIM Volume 11, April 1996 207

Table 3. Practitioner Performance on Spirometric Interpretation

Internist Agree Disagree % Correct

KACH 1 0 1 0 2 9 2 81.8 3 9 7 56.2 4 9 7 56.2 5 2 6 16 6 2 0 100 7 0 2 0

KACH t o t a l 31 2 5 5 5 . 4

DACH 8 13 0 100 9 8 1 88.8

10 6 0 100 11 11 2 84.6 12 3 5 37.5 13 1 0 100 14 0 1 0 DACH t o t a l 4 2 9 8 2 . 3

vidual patients."

4. "The severity of airway obstruct ion should be based on FEV l ra ther t h a n FEVI/FVC."

It is likely tha t many general internis ts are unaware of these recommendat ions. We believe tha t lack of famil- iarity with these recommendations, and the failure of both community hospitals to have any standardized algorithm

for the interpretat ion of screening spirometry may have contr ibuted to the discrepancies found in our study.

Our resul ts revealed that general in ternis ts at two communi ty hospitals incorrectly interpreted a significant percentage of spirometric tests. The gold s tandard to which the internis ts ' interpretat ions were compared was

the interpretat ion agreed upon by two practicing, board-

certified academic pulmonologists. Although pulmonolo- gists themselves will often disagree on interpretat ions {as

in the three cases in our study), the two subspecial is ts were able to reach concordant interpretat ions in the ma- jority of cases us ing the same publ ished guidelines. Thus,

we feel that us ing this gold s tandard is adequate. The errors included both overinterpretation ("false

positives") and under interpre ta t ion ("false negatives"). While the majority of false-positive interpretat ions ("small airways disease" and "mild" spirometric abnormalities) are unlikely to have much clinical significance, they may cause pat ients to be subjected to unnecessa ry testing or

medications, or to adverse actions by life insurance com-

panies. Likewise, disagreements about nomencla ture are unlikely to cause ha rm as long as the underlying process is identified, understood, and addressed; however, s tan- dardization of terminology does serve a useful purpose in both clinical practice and research.

The study's most d is turbing finding was that possible

restriction and upper airway obstruct ion may go unrecog- nized by general internists , a l though further testing would have to be done to confn-m the abnormali t ies found

by spirometry. In pat ients with early restrictive lung dis- ease or upper airway obstruction, the spirometric abnor-

mality may provide the only clue for making a timely diag- nosis and intervention. The consequences of missing these two diagnoses could be devastating. Also concern-

ing was the finding that restrictive pat terns were occa-

sionally interpreted as obstructive ventilatory defects. Be- cause the FEV1 was reduced along with the FVC, it

appears the interpret ing physicians were ignoring normal FEV1/FVC ratios and incorrectly a s suming only obstruc- t ion was present. This could lead to init iat ion of expensive

bronchodilator therapy when it is not indicated. Our assumpt ion that the ATS s ta tement was not

widely disseminated to general internis ts and that this possibly contr ibuted to inaccurate diagnoses is not a con-

denmat ion of either the pu lmonary or general in ternal medicine communit ies . It is likely tha t m a n y similar im- por tant articles are never reviewed by general internists .

Among the reasons for this are the large n u m b e r of sub- specialty journals , the lack of sufficient cont inuing medi- cal educat ion for busy internists , and the absence of m a n y subspecial ty journa l s in local libraries.

We believe that the subspecial ty conmluni ty has an obligation to provide ongoing educat ion and assis tance to

the general internist . The findings that 29% of the general in ternis ts were responsible for 74% of the inaccurate in- terpretat ions and that one hospital was the source of 74%

of the inaccurate interpretat ions provided important qual- ity improvement information and helped target specific in- dividuals and locations in need of reeducat ion to ensure

diagnostic effectiveness. Several l imitat ions in our s tudy are worth noting. As

a retrospective analysis performed over a relatively short period of time, it was susceptible to the bias of both the authors and those individuals working at the hospitals

dur ing this time. The s tudy compared interpretat ions ren- dered by generalists in normal, busy- practices with those

of pulmonologists who were aware they were involved in a quality improvement project. In an at tempt at minimizing

bias, the pulmonologists were bl inded to the general in- ternist 's interpretat ions. Also, the possibility exists that

for pulmonologists in a busy practice there would have been more discordance between the subspecialists. The use of the interpretat ional algorithm was intended to min-

imize this possibility. We conclude that in close to one third of spirometric

tests reviewed, the interpretat ions of a group of general in ternis ts differed significantly from those of two board-

certified puhnonologists who followed publ ished guide- lines. As participating doctors were not alerted before- hand tha t their ability to interpret screening spirometry resul ts was to be assessed, we feel tha t our resul ts accu- rately reflect the cur ren t level of general internists" exper-

tise in spirometric interpretat ion at these two inst i tut ions.

208 Hnat iuk et aI., Internists" Spirometric Interpretations JGLM

A l t h o u g h a few of t h e i n t e r n i s t s were r e s p o n s i b l e for t h e

major i ty of d i s c o r d a n c e , t h e r e will a lways be i n t e r n i s t s

t h a t a re b e t t e r t h a n o t h e r s in i n t e r p r e t i n g a wide r a n g e of

cl inical r e s u l t s , t h u s m a k i n g o u r r e s u l t s more , n o t less ,

gene ra l i zab le to t h e m e d i c a l c o m m u n i t y a s a whole . To

conf i rm th i s belief, however , f u r t h e r r e s e a r c h involving

m o r e i n t e r n i s t s is n e c e s s a r y . Unt i l t h a t t ime, we r e c o m -

m e n d t h a t all p h y s i c i a n s w i th t h e c r e d e n t i a l s to i n t e r p r e t

s p i r o m e t r y c o n s i d e r rev iewing t h e l a t e s t ATS gu ide l i ne s

a n d p e r f o r m i n g per iod ic qua l i ty cont ro l of t he i r i n t e r p r e -

t a t i ons . C o n t i n u e d p h y s i c i a n e d u c a t i o n a n d b r o a d e r d i s -

s e m i n a t i o n of n e w in t e rp re t a t i ve s t r a t eg i e s s h o u l d lead to

co r r ec t i on of ex i s t ing d i s c r e p a n c i e s a n d i m p r o v e d p a t i e n t

care .

The authors wish to thank Mrs. Robin Howard from the Walter Reed Army Medical Center Department of Clinical Investiga- tion for her assistance with statistical interpretation,

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