what are internists looking for?

1
JGIM LETTERS TO THE EDITOR Comorbidity and Length of Stay: Statistically Significant? To the Editor:--Matsni et al.1 report that comorbidity as mea- sured by the Charlson index was associated with a statistically significant increase in length of stay for patients hospitalized with chest pain. The partial R 2 for comorbidity in their multivariate model suggests that about 0.3% of the total variation in length of stay was independently explained by comorbidity. Moreover, of the variation explained, comorbidity accounted for about 0.7% (.0034/.5103, from Table 4). Adjusting for multiple comparisons (at least 18 in the multivariate analysis), I would guess that the overall importance of comorbidity may not be statistically signifi- cant. In fact, what is surprising about these results is that comor- bidity independently explained such a small amount of the varia- tion in length of stay. It seems that physicians generally ignored complicating noncardiac medical factors in treating patients with chest pain. Whether this is good or bad is unclear. All in all, the data suggest that, for chest pain hospitalizations, collecting infor- mation on comorbidity provides very little useful information for health services researchers or resource utilization managers.-- DAI~II~LJ. CHlgR, MD, Palo Alto VA Health Care System, Calif. REFERENCES 1. Matsui K, Goldman L, Johnson P, Kuntz K, Cook E, Lee T. Comor- bidity as a correlate of length of stay for hospitalized patients with acute chest pain. J Gen Intern Med. 1996; 11:262-8. In reply:--Dr. Cher has apparently misread Table 4 and cited the partial R2 for "Rales on initial examination"--the line below the information on Charlson index scores. Nevertheless, his ob- servation that comorbidity score seems to explain only a small percentage of the variability in length of stay in this population is worth addressing, since the correct partial R 2 was .005. In the overall population of patients with chest pain, the major "drivers" of length of stay were, not surprisingly, the diagnosis of acute my- ocardial infarction (R2 - . 12), performance of coronary artery by pass graft surgery (R2 - . 19), and the occurrence of complications such as congestive heart failure (R2 - .05) and recurrent ischemic pain (R2 = .06}. Among uncomplicated patients, however, comor- bidity score accounted for about as much of the variability in length of stay as a prior history of acute myocardial infarction, and a Charlson score of four or more was associated with an ad- justed increase in length of stay of 41% compared to patients with scores of 0 to 1. For example, this increase in comorbidity score would be associated with an increase in length of stay of 1.8 days compared to the mean length of stay of 4.5 days seen among pa tients with Charlson scores of 0 or 1. We would note that our data also demonstrate a clear "dose-response" effect between comor- bidity score and length of stay. Therefore, we conclude that co- morbidity as measured with Charlson index can improve analy- ses of length of stay for patients with acute chest pain. Whether other indices of comorbid conditions might provide even greater information remains to be determined.--THoM~ H. LEE, MID. Partners Community HealthCare, Inc., Boston, Mass. 500 What are Internists Looking For? To the Editor;---Clinical practice guidelines are proliferating. Although some physicians worry about their impact on clinical autonomy and satisfaction with clinical practice, most physicians appreciate their potential benefit. Only recently have investiga- tors begun to analyze what specific features make for effective practice guidelines. In their article, Hayward et al. nicely identify some of those features such as the importance of concise recom- mendations, the inclusion of a synopsis of supporting evidence and quantification of benefit.1 One area that was not addressed in their study is the impor- tance of adequate dissemination of information. Practice guide- lines can be of great benefit to clinicians. They also imply a stan- dard of care. However, guidelines are not helpful if physicians do not know of their existence. Frequently, this is due to numerous societies publishing guidelines in their own subspecialty jour- nals, many or most of which general internists do not read on a regular basis. A Medline search of practice guidelines for the year 1995 yielded 38 articles of potential importance to general inter- nists. These 38 articles were distributed among thirty-one differ- ent journals. Thirty three (87%) of the practice guidelines were published in subspecialty journals. The articles cover important issues such as the management of diabetes, 2 osteoarthritis, 3 and diverticulitis.4 To address this problem, 1 would like to suggest that a widely-circulated journal for general internists, such as JGIM, regularly publish an annotated bibliography of clinical practice guidelines. As more practice guidelines are published and their importayme grows, we cannot say that ignorance is bliss.--B~ M. /kBOFF, MD, Medical Center of Delaware, Newark. REFERENCES 1. Hayward RS, Wilson MC, Tunis SR, Guyatt GH, Moore K, Bass EB. Practice guidelines, What are internists looking for? J Gen In- tern Med. 1996:11 : 176-8. 2. American Diabetes Association. Clinical practice recommenda- tions 1995. Diabetes Care. 1995;18(Suppl}: 1-96. 3. Hochberg MC, Altman RD. Brandt KD, et al. Guidelines for the medical management of osteoarthritis. Part 1. Osteoarthritis of the hip. Arthritis Rheum. 1995:38:1535-40. 4. Roberts P. Abel M, Rosen L. et al. Practice parameters for sigmoid diverticulitis. The Standards Task Force Amei-ican Society of Co- lon and Rectal Surgeons. Dis Colon Rectum. 1995;38(2]: 125-32. In reply:--The authors agree entirely with Dr. AbofFs obser- vation that general internists could benefit from a widely avail- able annotated bibliography of clinical practice guidelines. In- deed, the Guideline Appraisal Project, which conducted the Practice Guidelines survey upon which our article is based, has more recently initiated an effort to build an inventory of evidence- based practice guidelines together with structured abstracts of as many as possible. This eflbrt is supported by a grant from the Na- tional Library of Medicine and is now getting underway. Informa- tion about the project and a rapidly growing inventory can be found on Internet at http://hiru.mcmaster.ca/CPG.--ROBERT I-InYw~, MD, McMaster University, Hamilton. Ontario, Canada.

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JGIM

LETTERS TO THE EDITOR

Comorbidity and Length of Stay: Statistically Significant?

To the Editor:--Matsni et al.1 repor t t h a t comorbid i ty as mea-

su red by the Cha r l son index was associated with a statist ically

s igni f icant inc rease in l eng th of s t ay for p a t i e n t s hospi ta l ized wi th

ches t pain. The pa r t i a l R 2 for comorbid i ty in the i r mu l t iva r i a t e

model s u g g e s t s t h a t abou t 0.3% of the total va r i a t ion in length of

s t ay was i ndependen t ly exp la ined by comorbidi ty. Moreover, of

the va r i a t ion explained, comorbid i ty a c c o u n t e d for a b o u t 0.7%

( .0034/ .5103 , from Table 4). Adjus t ing for mul t ip l e c o m p a r i s o n s

(at l eas t 18 in the mul t iva r i a t e analysis) , I would g u e s s t h a t the

overall impor t ance of comorbid i ty m a y not be s ta t i s t i ca l ly signifi-

cant .

In fact, w h a t is s u r p r i s i n g a b o u t these r e s u l t s is t h a t comor-

b idi ty i ndependen t ly exp la ined s u c h a sma l l a m o u n t of the var ia-

t ion in length of s tay. It s e e m s t h a t p h y s i c i a n s genera l ly ignored

compl ica t ing nonca rd i ac medica l factors in t r ea t ing pa t i en t s with

ches t pain. Whe the r th is is good or bad is unc lea r . All in all, the

d a t a sugges t tha t , for ches t pa in hosp i t a l i za t ions , col lect ing infor-

ma t ion on comorbid i ty provides very li t t le usefu l in format ion for

hea l t h services r e s ea r che r s or r esource u t i l iza t ion m a n a g e r s . - -

DAI~II~L J . CHlgR, MD, Palo Alto VA Health Care Sys tem, Calif.

REFERENCES

1. Matsui K, Goldman L, Johnson P, Kuntz K, Cook E, Lee T. Comor-

bidity as a correlate of length of stay for hospitalized patients with acute chest pain. J Gen Intern Med. 1996; 11:262-8.

In reply:--Dr. Cher h a s appa ren t l y m i s r ead Table 4 and ci ted

the par t i a l R 2 for "Rales on in i t ia l e x a m i n a t i o n " - - t h e l ine below

the informat ion on Cha r l son index scores. Nevertheless , his ob-

se rva t ion t h a t comorbid i ty score s eems to expla in only a smal l

pe rcen tage of the var iab i l i ty in l eng th of s t ay in th i s popu la t ion is

wor th address ing , s ince the correct par t i a l R 2 was .005. In the

overall popu la t ion of p a t i e n t s wi th ches t pa in , the majo r "drivers"

of l eng th of s t ay were, not surpr i s ing ly , the d i agnos i s of acu t e my-

ocardia l infarc t ion (R 2 - . 12), pe r formance of coronary a r te ry by

p a s s graft su rge ry (R 2 - . 19), and the occur rence of compl ica t ions

s u c h as congest ive h e a r t fai lure (R 2 - .05) and r ecu r ren t i s chemic

pa in (R 2 = .06}. Among u n c o m p l i c a t e d pa t ien t s , however, comor-

bidi ty score accoun ted for a b o u t as m u c h of the var iab i l i ty in

l eng th of s t ay as a pr ior h i s to ry of acu t e myocard ia l infarct ion,

and a C h a r l s o n score of four or more was a s soc i a t ed wi th an ad-

j u s t e d inc rease in l eng th of s t ay of 41% compared to pa t i en t s wi th

scores of 0 to 1. For example , th i s inc rease in comorbid i ty score

would be a s soc i a t ed wi th an inc rease in l eng th of s t ay of 1.8 days

compared to the m e a n leng th of s t ay of 4.5 days seen a m o n g pa

t i en t s wi th Cha r l son scores of 0 or 1. We would note t h a t our d a t a

a lso d e m o n s t r a t e a c lear "dose-response" effect be tween comor-

b idi ty score and leng th of s tay. Therefore, we conc lude tha t co-

morbid i ty as m e a s u r e d wi th Cha r l son index can improve analy-

ses of l eng th of s t ay for p a t i e n t s wi th acu t e ches t pain. Whe the r

o ther indices of comorbid cond i t ions migh t provide even g rea te r

in format ion r e m a i n s to be d e t e r m i n e d . - - T H o M ~ H. LEE, MID.

Partners Communi ty HealthCare, Inc., Boston, Mass.

500

What are Internists Looking For?

To the Editor;---Clinical pract ice gu ide l ines a re proliferat ing.

Al though some p h y s i c i a n s worry abou t the i r impac t on cl inical

a u t o n o m y and sa t i s fac t ion wi th cl inical practice, m o s t phys i c i ans

apprec ia te the i r po ten t ia l benefit . Only recent ly have inves t iga-

tors b e g u n to ana lyze w h a t specific f ea tu res m a k e for effective

prac t ice guidel ines . In the i r article, Hayward et al. n icely identify

some of those fea tures s u c h as the impor t ance of concise recom-

menda t ions , the inc lus ion of a synops i s of s u p p o r t i n g evidence

and quan t i f i ca t ion of benefit.1

One a rea t h a t was not a d d r e s s e d in the i r s t u d y is the impor-

t ance of a d e q u a t e d i s s e m i n a t i o n of informat ion. Pract ice guide-

l ines can be of g rea t benefi t to c l in ic ians . They also imply a s t an -

dard of care. However, gu ide l ines are not helpful if p h y s i c i a n s do

not know of the i r exis tence. Frequent ly , th is is due to n u m e r o u s

socie t ies p u b l i s h i n g gu ide l ines in the i r own subspec i a l t y jour -

na l s , m a n y or m o s t of which genera l i n t e rn i s t s do not read on a

r egu la r bas i s . A Medline s ea r ch of prac t ice gu ide l ines for the yea r

1995 yielded 38 a r t ic les of po ten t ia l impor t ance to genera l inter-

n is ts . These 38 ar t ic les were d i s t r ibu ted a m o n g th i r ty-one differ-

en t journa l s . Thir ty th ree (87%) of the pract ice gu ide l ines were

p u b l i s h e d in subspec i a l t y jou rna l s . The ar t ic les cover i m p o r t a n t

i s s u e s s u c h as the m a n a g e m e n t of d iabetes , 2 os teoar thr i t i s , 3 and

divert icul i t is . 4 To a d d r e s s th i s problem, 1 would like to sugges t

t h a t a wide ly-c i rcu la ted j o u r n a l for genera l in te rn i s t s , s u c h as

JGIM, regular ly pub l i sh an a n n o t a t e d b ib l iography of c l inical

prac t ice guidel ines . As more prac t ice gu ide l ines are pub l i shed

and the i r importayme grows, we c a n n o t say t h a t ignorance is

b l i s s . - - B ~ M. /kBOFF, MD, Medical Center o f Delaware,

Newark .

REFERENCES

1. Hayward RS, Wilson MC, Tunis SR, Guyatt GH, Moore K, Bass EB. Practice guidelines, What are internists looking for? J Gen In-

tern Med. 1996:11 : 176-8. 2. American Diabetes Association. Clinical practice recommenda-

tions 1995. Diabetes Care. 1995;18(Suppl}: 1-96. 3. Hochberg MC, Altman RD. Brandt KD, et al. Guidelines for the

medical management of osteoarthritis. Part 1. Osteoarthritis of the

hip. Arthritis Rheum. 1995:38:1535-40. 4. Roberts P. Abel M, Rosen L. et al. Practice parameters for sigmoid

diverticulitis. The Standards Task Force Amei-ican Society of Co-

lon and Rectal Surgeons. Dis Colon Rectum. 1995;38(2]: 125-32.

In reply:--The a u t h o r s agree ent i re ly wi th Dr. AbofFs obser-

va t ion t h a t genera l i n t e rn i s t s could benefi t from a widely avail-

able a n n o t a t e d b ib l iography of cl inical p rac t ice guidel ines . In-

deed, the Guidel ine Appra i sa l Project, wh ich conduc ted the

Pract ice Guide l ines survey upon wh ich our ar t ic le is based, h a s

more recent ly in i t ia ted an effort to bu i ld an inventory of evidence-

b a s e d prac t ice gu ide l ines toge ther wi th s t r u c t u r e d a b s t r a c t s of as

m a n y as possible . This eflbrt is s u p p o r t e d by a g r a n t from the Na-

t ional Library of Medicine and is now get t ing underway. Informa-

tion abou t the project and a rap id ly growing inventory can be

found on In te rne t a t h t t p : / / h i r u . m c m a s t e r . c a / C P G . - - R O B E R T

I - I n Y w ~ , MD, McMaster University, Hamilton. Ontario, Canada.