PharmLab

Linking Laboratory and Pharmacy

Opportunities for Reducing Errors and Improving Care

Gordon D. Schiff, MD; David Klass, MD; Josh Peterson, MD; Gaurav Shah, MD; David W. Bates, MD, MSc

A myriad of errors and lost improvement opportunities result from failure of clinicallaboratory and pharmacy information systems to effectively communicate. Pharma-cotherapy could benefit from enhanced laboratory-pharmacy linkage with respect to(1) drug choice (laboratory-based indications and contraindications), (2) drug dos-

ing (renal or hepatic, blood level–guided adjustments), (3) laboratory monitoring (laboratory sig-nals of toxicity, baseline and ongoing monitoring), (4) laboratory result interpretation (drug in-terfering with test), and (5) broader quality improvement (surveillance for unrecognized toxicity,monitoring clinician response delays). Linkages can be retrospective or real-time. Many organi-zations could benefit now by linking existing pharmacy and laboratory data. Greater improve-ment is possible through implementation of electronic order entry with real-time decision supportincorporating linked laboratory and pharmacy data. While many guidelines, admonitions, and rulesexist regarding drugs and the laboratory, substantial new knowledge and evidence in this area areneeded. Focusing on these unmet needs and accompanying logistical challenges is a priority.

Arch Intern Med. 2003;163:893-900

A physician prescribes potassium supple-mentation for a patient who is hyperka-lemic, fails to adjust the dose of gentami-cin in a patient with impaired renalfunction, continues a theophylline infu-sion in a patient who has toxic theophyl-line levels, continues an antibiotic for a pa-tient whose blood cultures show anorganism resistant to that drug, or fails toperform recommended monitoring of liveror muscle enzyme tests in patients taking

troglitazone or cerivastatin sodium. Theseare examples of errors that have oc-curred commonly, yet could have beenprevented if laboratory and pharmacy in-formation systems communicated more ef-fectively.1-7

Drug errors related to laboratory is-sues commonly injure patients, both in-side and outside the hospital. One studyfound that adverse drug events occurredin 6.5 of 100 admissions; 28% of these ad-verse drug events were judged prevent-able. Errors were most often due to drugdosing and selection problems related tolaboratory parameters.8 Using computer-ized screening, Hulse et al9 found that 5%of 13727 patients had potential drug prob-lems, with drug-laboratory issues repre-senting the leading reason (44.9% of thepositive screens). In another inpatientstudy of more than 2100 pharmacist-detected medication errors, the leadingtype of error identified (13.9% of all er-rors) was excessive dosing for patients withimpaired renal and hepatic function.10 Ad-verse drug events also occur frequently in

From the Department of Medicine, Cook County Hospital (Drs Schiff and Shah), RushMedical College (Dr Schiff), Chicago, Ill; State of Illinois Department of Mental Health,University of Chicago Medical School (Dr Klass); Center for Health Services Research,Vanderbilt University Medical Center, Nashville, Tenn (Dr Peterson); and Division ofGeneral Internal Medicine, Brigham and Women’s Hospital and Partners HealthcareInformation Systems, Boston, Mass (Dr Bates). Dr Klass is now with VigiLanzCorporation, St Paul, Minn. Dr Bates has received honoraria for speaking from theEclipsys Corporation, Boca Raton, Fla, and from Automated Healthcare; is a coinventoron patent No. 6029138 held by Brigham and Women’s Hospital on the use of decisionsupport software for medical management, licensed to the Medicalis Corporation,Waterloo, Ontario; holds a minority equity position in Medicalis Corporation; is aconsultant and serves on the advisory board for McKesson MedManagement, BrooklynPark, Minn; is on the clinical advisory boards for Zynx Inc, Beverly Hills, Calif, andSoCurious Inc, San Francisco, Calif; and is a consultant for Alaris, San Diego, Calif.Drs Schiff, Peterson, and Shah have no relevant financial interest in this article.

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nursing homes, where an evengreater proportion are prevent-able.11 In this setting, insufficientlaboratory monitoring, especially foranticoagulation therapy, is a lead-ing cause of error.11 Although fewerdata are available for outpatients,medication-related problems arecommon outside the hospital, anddeficiencies in monitoring are espe-cially prominent.12 One recent studyfound that 79% of adverse drugevents detected by linking drugswith laboratory “signals” went rou-tinely unrecognized.13

Laboratory information is criti-cal to selecting and managing medi-cations, yet the clinical laboratory andpharmacy are remarkably discon-nected.1,13,14 While the pharmacy is re-sponsible for filling orders and dis-pensing medications, the laboratorymonitors various effects of these ad-ministered chemicals. Despite thiscomplementary relationship be-tween the clinical laboratory and thepharmacy, these 2 departments, theirpersonnel, their work processes, andparticularly their information sys-tems rarely communicate.14,15 This isespecially true in the outpatient set-ting, where the vast majority of drugsand tests are ordered.12

This disconnect even carriesover to quality improvement ef-forts, which often fail to leveragelaboratory and pharmacy data to re-duce errors and improve care.16-19

For example, at the laboratory end,recent symposia on improving theclinical use of laboratory informa-tion fail to even mention linkageswith medications,20-23 and an other-wise comprehensive pharmacist-edited book from the Institute forSafe Medication Practices on pre-venting medication errors barelytouches on the subject of better con-nection to the laboratory.24

LINKING LABORATORYAND PHARMACY:

RATIONALE AND MODEL

Many medication errors could beprevented if laboratory and phar-macy information systems “talkedwith each other.”16,25 However, frankerrors are just the tip of the ice-berg. Communication between these2 systems, linked with appropriateknowledge-based rules, has broadpotential to improve the quality ofmedical care.9,26-29 With such link-ages, drug toxicity can be more re-liably prevented and more promptly

recognized and addressed when itdoes occur.

Linking tests and treatmentscan improve the utilization and qual-ity of both laboratory testing andpharmacotherapy, as well as createopportunities for improved out-comes and learning. Such linkagescan either be retrospective, linkingdownloaded laboratory and phar-macy files, or real-time via emerg-ing intelligent order-entry systems.Although most hospitals and healthsystems do not currently have the ca-pability for real-time linkage, virtu-ally all could, but fail to, retrospec-tively tap into existing systems tolink laboratory and pharmacy data,thereby missing improvement op-portunities residing in existing datasystems.

In this article, we describe 10ways in which laboratory and phar-macy data can be related to im-prove patient care (Table 1).

Drug Selection

Powerful software has been devel-oped to check whether a patient’sdrug prescription conflicts with hisor her insurance company’s formu-lary, although the benefits of this (if

Table 1. Ten Ways Lab and Pharmacy Can Be Linked to Improve Care

Category Concept Examples (Drug—Lab Pair)*Special Role for theComputer/Linkages

Drug selection 1. Lab finding contraindicates drug + Pregnancy test—ACE inhibitor↑SUN/Cr—metformin hydrochloride

Prevents prescription writing ordispensing

2. Lab finding suggests indication for drug ↑ TSH—levothyroxine sodium↑ Cholesterol—lipid-lowering treatment

Generates timely reminders,tracking intervention

Dosing 3. Lab finding affecting drug dose ↑ Creatinine—digoxin, vancomycinhydrochloride

Performs dose calculations basedon age, sex, lab value, weight

4. Drug requiring lab measure for titration Warfarin sodium—PT/INRAnticonvulsants—drug levels

Statistical process control dosingadjustment charts

Monitoring 5. Abnormal lab value signaling toxicity Liver enzymes—isoniazid, glitazones↓ HCT, WBC—chloramphenicol

Triggers alert, assesses likelihood

6. Drug warranting lab value monitoring for toxicity Clozapine—WBCAmphotericin B—creatinine

Oversees scheduling of both baselineand serial monitoring tests

Lab interpretation 7. Drug influencing or interfering with lab finding Carbamazepine—free thyroxineQuinolones—false-positive urine opiates

Warns against/interpretsfalse-positives and false-negatives

8. Drug impacting on response to lab finding Insulin—↓ or ↑ glucosePenicillin— + RPR

Resets alarm threshold for treatedpatients

Improvement 9. Drug toxicity/effects surveillance Detects signals of previouslyundocumented reaction (eg,hepatotoxicity)

Data mining of lab and drug data togenerate new hypotheses of drugeffects

10. Quality oversight Treatment delay after abnormal results(↑ TSH, ↑ K+, + blood culture) andinitiation of appropriate treatment

Monitors time interval between labtesting and prescription change,adequacy/appropriateness of labmonitoring

Abbreviations: ACE, angiotensin-converting enzyme; Cr, creatinine; HCT, hematocrit; INR, international normalized ratio; K+, potassium; lab, laboratory;PT, prothrombin time; RPR, rapid plasma reagin; SUN, serum urea nitrogen; TSH, thyrotropin; WBC, white blood cell count.

*Plus sign indicates positive.




any) are largely financial.30,31 Incontrast, despite its proven clinicalbenefit,26 few institutions have thecapability of checking laboratory-based safety contraindications. Forinstance, a recent survey showed thatno major hospital or clinic in Chi-cago, Ill, had mechanisms in placeto automatically prevent prescrib-ing potassium in the setting of anelevated serum potassium level,an angiotensin-converting enzymeinhibitor when a positive preg-nancy test has been recorded, ormetformin hydrochloride when azo-temia is present (G.D.S., unpub-lished survey, February 2001).

On the other hand, certainclinical laboratory abnormalities rep-resent indications for a particulardrug treatment. A markedly el-evated thyrotropin (TSH) level with-out a subsequent order for levothy-roxine sodium (or a repeat test), ora repeatedly elevated glucose or he-moglobin A1c level with no hypogly-cemic drug prescription, repre-sents a laboratory abnormalitymandating pharmacy actions andshould generate alerts in their ab-sence.32,33

Dosing

A review of patients with digoxintoxicity showed that 32% had renalinsufficiency, in most cases with-out proper dosing adjustment.34 Re-cently, we studied medication or-ders for patients with decreasedcreatinine clearance. Among drugsthat were renally excreted or neph-rotoxic, 70% of orders were writ-ten for an inappropriately high doseor frequency.2 Thus, despite de-cades of published guidelines35

supplementing the explicit instruc-tions on each drug’s package label,physicians clearly need more reli-able tools to ensure proper renal dos-ing.4 It is not realistic to expect cli-nicians to remember the hundredsof drugs requiring altered doses aswell as to think through which pa-tients need such adjustments and towhat degree. Any systematic effortto translate dosing guidelines into ac-tual practice must automate the cal-culation of both creatinine clear-ance (which requires knowledge ofpatient’s serum creatinine level, age,and weight) and the adjusted dos-

age. Although there is no analo-gous method to calculate hepaticclearance, elevated aminotransfer-ase levels, high bilirubin level, or lowalbumin levels suggest that a lowerdose of hepatically cleared medica-tions is needed.36,37

In addition to initial dose se-lection, many drugs, such as anti-convulsants, anticoagulants, andendocrine or hormonal drugs (eg, in-sulin, thyroxine, erythropoietin),require ongoing titration based onmeasurement of serum drug levelsor other clinical laboratory indi-cators of their biological effects.Currently, there are wide varia-tions in testing frequency, appro-priateness, and achievement oftarget levels.38,39

How often should such testsbe done, and how should dosing beadjusted on the basis of the results?Drug-laboratory–linked computer-ized data facilitate graphic flowcharting of laboratory results anddrug dosing. Using statistical pro-cess control, a proven tool in otherindustries, clinicians could more sci-entifically respond to changes in thetest results.40 This method can helpclinicians and even patients graphlaboratory results (such as glucoseor anticoagulation tests) in relationto drug dosages over time. Suchcharts can help determine when tomodify drug dose by determiningwhether variation in levels is ran-dom (and drug dose should not be“tampered” with) or truly out of con-trol (necessitating a change).41-43 Us-ing statistical process control meth-ods, diabetic patients have beenmore successful at achieving targetcontrol levels than the current phy-sician hit-and-miss approach, withone practice showing a drop in av-erage fasting blood glucose levelfrom 187 to 110 mg/dL (10.4 to 6.1mmol/L) and a decrease in hemo-globin A1c concentration from 10.5%to 7.2%.44

Monitoring

A laboratory test result could be“smarter” if it “knew” which drugsa patient was taking. For example,apparently minor liver abnormali-ties assume greater importance if apatient is receiving a hepatotoxicdrug.37,45,46 Similarly, hypokalemia

has special meaning for a patient tak-ing digoxin.47-49 Drug-laboratory in-terconnections need to couple in-formation on the starting time anddate of a prescription with the in-telligence to interpret changes inlaboratory results over time. Thus,patients’ previous laboratory re-sults become important to detectchanges (not just normal or abnor-mal) in laboratory parameters—subtle changes that otherwise mightbe ignored.50

Certain drugs require baselineor scheduled laboratory monitor-ing. Troglitazone was removed fromthe US market because of infre-quent (1.9/100) but potentially fa-tal hepatotoxicity.51 The drug’smanufacturer and the US Food andDrug Administration initially ar-gued that troglitazone was safe if pa-tients were properly monitored.However, despite a series of 4 in-creasingly strong warnings for livertest monitoring added to the drug’sofficial label, a study at one aca-demic hospital showed that less than5% of the patients actually receivedthe monthly testing the Food andDrug Administration warned was aprecondition for safe use of thedrug.7 Similar failure to monitor wasrecently documented for statin cho-lesterol-lowering agents.52 Consid-ering the logistics of coordinatingsuch drug-related laboratory moni-toring, integrated computerizedscheduling and tracking would ap-pear to be a prerequisite for a safesystem.53

Laboratory Interferenceand Interpretation

Earlier work by Friedman et al54 andYoung55 and more recent studies byFinnish investigators56-59 (includ-ing Gronroos et al56 and Forsstromet al57) have shown the importanceof the laboratory knowing whichdrugs the patient is taking to avoidmisinterpreting results in instanceswhere drugs interfere with labora-tory measurement. One survey ofspecimens sent for hormone stud-ies found that 11% were from pa-tients currently taking one or morepotentially interfering drugs, andnearly 40% of the patients tested forTSH had such conflicts.58,60 This is-sue looms sufficiently large that the




Finnish laboratory scientists cre-ated a database cataloging their pa-tients’ drug profiles, and demon-strated improved accuracy ininterpretation of their laboratory’stest results.61 Elsewhere, most drug-laboratory conflicts go undetected,while others are simply unknownbecause of scant research on in vitrolaboratory interference or in vivobiologic effects.62 Where conflictshave been identified, we generallylack evidence about their magni-tude and clinical significance.

Even simple laboratory fol-low-up questions such as, “Does thisglucose level of 300 mg/dL requireurgent follow-up?” could be moreeasily answered if it was knownwhether the patient was taking glu-cose-lowering medication (ie, was aknown diabetic). The response toanemia in a patient taking erythro-poietin should be different from thatfor a falling hematocrit in a patienttaking a nonsteroidal anti-inflam-matory drug.63 Knowing not onlywhat drugs a patient is taking butwhen they were taken is importantfor the laboratory to interpret druglevels as well as to ensure properlytimed specimen collection.39

Learning and Improvement

Data mining with the use of power-ful search algorithms and massivelinked databases represents a newmodel for scientific research thatpromises to substantially improveclinical care.19,64-68 Advances emerg-ing from the Human Genome Projectillustrate the enormous potential ofwhat previously might have been con-sidered unsystematic data collectionbut, when linked to phenotype data,permits discovery of new knowl-edge.69 Similar advances in knowl-edge of drug effects and outcomes canresult from the linking of laboratoryto pharmacy. While associations be-tween a clinical laboratory abnormal-ity and pharmaceutical agents shouldbe considered hypotheses for futuretesting, these signals can be invalu-able for earlier detection of adversedrug effects.64,70

On a more mundane improve-ment level, laboratory-pharmacy link-ages can help evaluate the timelinessof responses to abnormal laboratoryresults, or the adequacy or appropri-

ateness of monitoring patients tak-ing a particular drug. This quality as-surance role has been deployed touncover inappropriate laboratory test-ing (orders for drug levels for pa-tients not taking or not in a steadystate for a drug, or excessively re-peated levels without dose change) orto document failure to obtain recom-mended monitoring.7 1 - 7 3 Mis-matches in microbiology data and an-tibiotic prescriptions have identifiedpatients given antibiotics to whichtheir infections were resistant orbeing treated without proper cul-tures having been obtained.67 Popu-lation diabetic outcomes can betracked by using pharmacy records toidentify diabetic patients taking hy-poglycemic medications and thenlinking records to serial renal func-tion.74-76 Given properly linked labo-ratory-pharmacy databases, suchquestions could be evaluated for a par-ticular drug, laboratory test, physi-cian, or time frame (to establish his-torical quality trends).

LINKING LABORATORYAND PHARMACY:

CURRENT APPROACHES

Retrospective Linkage

Retrospective electronic data havebeen used to perform many of the 10functions we describe in Table 1. Evenwhen laboratory and pharmacy datareside in separate systems and are notconcurrently interfaced, these datacan be retrospectively linked to bet-ter treat and protect patients.

At the simplest level, some hos-pitals generate reports for patients re-ceiving prescribed drugs that re-quire renal adjustment, thenmanuallylook up their creatinine values.77 Thistype of drug-laboratory “bridging”function has been an invaluable con-tribution of clinical pharmacists, al-though it is labor intensive and re-quires “rework” that could be avoidedwith a prospective system. Althoughsuch reports are by definition retro-spective, they have played a valuablerole in identifying problem orders andimproving care.78,79

A more powerful and efficientretrospective linkage involves themerging and screening of files fromlaboratory and pharmacy informa-tion systems. One of us (D.K.) down-

loads more than 1 million drug andlaboratory records annually from the19 Illinois state psychiatric hospi-tals and links them to evaluate a se-ries of quality indicators.71 “Clean-ing” the data to make it usable forsuch screening has required exten-sive programming, particularly forpharmacy data. An important in-sight emerging from this experi-ence is that pharmacy data files aremuch more complex and unstand-ardized than laboratory data. For ex-ample, 37 steps are required to con-vert the inpatient pharmacy data ofthe Illinois mental health phar-macy database into a standardizeddosing, frequency, and durationtable (laboratory data require fewerthan half that number).

Outpatient pharmacy files are of-ten less complex. Because widelyavailable programs such as Micro-soft Excel or Access can now easilyimport data files downloaded by in-formation technology staff, any phy-sician, pharmacist, or quality assur-ance nurse can create spreadsheets ordatabases that link pharmacy rec-ords with laboratory values for a givenpatient by means of simple sorting, fil-tering, and query tools. When bothlaboratory and pharmacy use a com-mon patient identifying number,matching the 2 datasets is straight-forward. A quality analyst can flag allrecords for patients meeting speci-fied criteria and create tables thatchronologically display merged labo-ratory and drug prescription data(Figure). Using this method, we un-covered more than 500 prescrip-tions in a single year for oral potas-sium supplementation (2.4% of allpotassium prescriptions) written anddispensed for patients with preexist-ing elevated serum potassium values(�5.3 mEq/L).1

Real-Time Linkage

Compared with retrospective ef-forts, implementation of physicianorder entry systems and electronicintegration of laboratory and phar-macy data that allow real-time de-cision support can have even greaterbenefits in each of our 10 concep-tual realms.80

When a laboratory test affectsa drug dose, displaying key labora-tory information at the time a drug




is ordered or when a pharmacist en-ters the order into the computer (eg,showing last phenytoin level whenphenytoin is ordered) can help cli-nicians make better decisions.81 Thecomputer can calculate an appro-priate dose based on the patient’s re-nal function, age, sex, and weight.One study evaluating the impact ofrenally adjusted dosing in hospital-ized patients found that such deci-sion support improved dosing ap-propriateness from 54% before theintervention to 67% afterward.2

Titrating medications with theresults of laboratory testing is one ofthe domains in which computer-ized decision support has been foundto be particularly helpful.82 For ex-ample, interactive computerized as-sistance with warfarin dosing hasbeen shown to improve the propor-tion of time a patient spends withinthe therapeutic range.83 In addi-tion, for many medications for whichdrug level monitoring can be per-formed, these results can be used tomake suggestions about when an-other level should be checked. De-cision support can reduce the num-ber of redundant levels by estimatingthe appropriate monitoring inter-val.38,84,85 In one study, more than80% of antiepileptic drug levels werefound to be inappropriate, and manywould have been avoided if real-time warnings had been presentedat the time the test was being or-dered.39,81

When laboratory tests signaldrug toxicity, studies have shownthat the computerized alerts can beused to limit the extent of an ad-verse drug event and enhance thetimeliness of interventions to mini-mize its harm.86,87 As the computerdetects a critical laboratory result fora patient receiving a particular drug,warnings are generated for a phar-macist to intervene or, more pow-erfully, such results are being com-municated immediately to providerselectronically by means of tools suchas 2-way pagers.88

Computerized decision sup-port has also been shown to increasethe likelihood that appropriate moni-toring will occur. Overhage and co-workers’ study89 of “corollary or-ders”—situations in which one orderimplies another—demonstrated thatdecision support dramatically in-

creases the likelihood that recom-mended laboratory monitoring or-ders were written. Compliance ratesof indicated monitoring (baseline andfollow-up platelet count and acti-vated partial thromboplastin time) forpatients receiving heparin increasedfrom 40.2% (control subjects) to77.4% in patients whose physicianswere presented with reminderscoupled with streamlined orderingscreens for laboratory tests linked todrug orders.89

Decision support can be criti-cal when a laboratory test contrain-dicates a certain medication. Whena patient is pregnant, angiotensin-converting enzyme inhibitors arecontraindicated. However, most sys-tems do not capture a positive preg-nancy test, especially if performedby the patient at home. Such infor-mation would also need to be en-hanced with simple rules (eg, preg-nancy does not last longer than 10months; after a delivery a woman isno longer pregnant) to keep it dy-namically updated.

Some situations are more com-plex to handle electronically be-cause they are asynchronous.90 Forexample, while a high TSH level of-ten indicates that an action shouldbe taken (eg, adding or increasingthe dose of levothyroxine), it oftenregisters after (rather than during)

an outpatient encounter. Implemen-tation of one inpatient ordering sys-tem linking medications and labo-ratory resulted in a 38% decrease inthe median time interval to act oncritical laboratory results.91

Finally, combined elements ofretrospective and real-time decisionsupporthaveprovedusefulforprovid-ingqualityoversightandimprovement.Severalstudieshavedemonstratedthatdrug-laboratorycombinationsareoneofthebesttools for identifyingadversedrugevents, inboth the inpatientandoutpatient settings.92-95 Relying to alargeextentonlaboratorysignalssug-gestinganadverseevent,Classenetal92

demonstratedan800%increase inthenumber of adverse drug events iden-tifiedcomparedwith thestandardap-proach (spontaneous reporting). Be-cause such an approach to screeningfor adverse drug events is so muchmoreefficient(moreproblemsdetectedwith less effort), it has made continu-ousmonitoring,previouslyunsustain-able, possible.93

Development of systems that en-sure appropriate follow-up of a spe-cific abnormality or laboratory-pharmacy signal is critical forachieving error-free tracking and ac-countability. Many studies demon-strate that abnormal results often donot receive timely or appropriate fol-low-up.3,91,96 Linked systems facili-

NAME UNITNO DATE RESULT GENERIC_NM QUANTITY

JONES, BILLJONES, BILLSMITH, MARYSMITH, MARYSMITH, MARYSTOKES, WILLSTOKES, WILLCULLEN, CORACULLEN, CORACULLEN, CORACULLEN, CORAPABST, POLLYPABST, POLLYKENNEDY, JOEKENNEDY, JOEKENNEDY, JOEKENNEDY, JOEKENNEDY, JOEKENNEDY, JOEKENNEDY, JOE

122441122441125565125565125565137995137995148341148341148341148341155103155103156828156828156828156828156828156828156828

03/11/9503/20/9505/16/9505/16/9511/19/9501/03/9501/03/9503/30/9504/01/9504/12/9506/14/9501/11/9504/12/9502/22/9503/06/9504/05/9505/09/9505/10/9505/23/9505/24/95

6.0

5.3

7.0

5.35.3

5.3

5.6

4.96.6

5.2

POTASSIUM CHLORIDE

POTASSIUM CHLORIDE

POTASSIUM CHLORIDE

POTASSIUM CHLORIDEPOTASSIUM CHLORIDEPOTASSIUM CHLORIDE

POTASSIUM CHLORIDE

POTASSIUM CHLORIDE

POTASSIUM CHLORIDE

POTASSIUM CHLORIDE

60

30

30

146030

240

240

20

30

Examples of actual errors disclosed when pharmacy records and laboratory data were merged and thensorted by patient and date. For example, the first record/row is from the laboratory computer, and thesecond is from the pharmacy database (patient names and clinic numbers changed).




tate both review by an individual pro-vider and systemwide qualityoversight by enabling organized sys-tems for intervention when clini-cians fail to follow up.

WHAT TO LINK:NEED FOR STANDARDS

AND RESEARCH

The current evidence base is thin re-garding which tests to link and atwhat thresholds. While many of theexamples we discuss appear to bereasonable starting places, our tax-onomy is merely an entry point forfuture research.

One information source for pre-scribers to consider is the officialFood and Drug Administration druglabeling—warnings to which, intheory, they are legally obliged to payheed. These “labeled” instructions ap-pear on the prescriber package in-serts and are reprinted in the Physi-cians’ Desk Reference.97 In Table 2we summarize laboratory-phar-macy interactions listed in the Phy-sicians’ Desk Reference for the mostcommonly prescribed, and the re-cently approved, oral medications.There are more than 500 laboratory-pharmacy interactions—an averageof 6.6 per drug. These interactions,with their associated requirementsand warnings, are so numerous thatit is unlikely that any unaided phy-sician could remember and manu-ally track all of them simulta-neously for all the drugs prescribedfor his or her patients.

However, linked alerts will notbe effective if users are overloaded

with a “blizzard” of poorly vali-dated warnings. This point has beenillustrated by pharmacists’ experi-ence of being deluged with a largenumber of computerized warningsof drug-drug interactions, many ofwhich are not evidence-based orconsistent among different commer-cial software products.98 As a re-sult, important warnings are over-looked, and pharmacists inactivatemany of the alerts.99,100 Indiscrimi-nantly adding hundreds of drug-laboratory interactions could fur-ther lead pharmacists and physiciansto ignore or inactivate many of thewarnings. A research agenda is verymuch needed to help sort out theusefulness of various tests, thresh-olds, and actions.101

FUTURE CHALLENGES

Paraphrasing Donabedian’s triad,102

(1) setting up the electronic infra-structure, (2) creating standard-ized laboratory-pharmacy linkageprocesses and clinical rules, and (3)demonstrating the benefit of suchlinkages on patient outcomes all posemajor challenges.

Progress in real-time orderingand feedback has been inhibited bythe cost of implementing full-scalelinked information systems. Manyphysicians have been reluctant to in-vest in the additional dollars and havefurther concerns about perceivedadded time burdens. Even wherecomputerized ordering is in place,building and maintaining the knowl-edge base is challenging, especially asincreasingly complex decision sup-

port is attempted. A recent survey ofinstitutions that have installed com-mercial systems with order entryfound that less than 10% were using“intelligent” rules that linked infor-mation from different systems suchas laboratory and pharmacy.103

A major problem has been that,lacking standardized and testeddrug-laboratory interaction rules,each institution finds itself reinvent-ing the wheel. Although vendors ad-vertise packages of ready-to-userules, none of these (either indi-vidual rules or rule sets) has beensubjected to formal testing or peerreview. The effort associated withmaintenance must be underscored,especially given the large numbersof medications being introducedeach year. Thus, a public compen-dium of evidence-based rules wouldbe extremely valuable.

In the future, pharmacogeno-mics, laboratory’s newest emergingdomain, will add a further level ofchallenge and complexity.104 Evi-dence suggests, for example, that cer-tain genotypes, such as allelic vari-ants of cytochrome P450, cansubstantially alter patients’ re-sponse to warfarin or the likelihoodof having a hypersensitivity reac-tion to phenytoin. This pushes theboundaries of laboratory-pharmacyinteractions, potentially redefining as“preventable errors” more and morereactions currently deemed to be “id-iosyncratic,” as well as moving us to-ward patient-specific targeting of drugactions.105,106

CONCLUSIONS

While much has been written about“managed care,” effectively manag-ing clinical care for both inpatientsand outpatients demands better in-tegration of clinical laboratory andpharmacy data. The evidence thatexisting data are not being opti-mally used is substantial, and acces-sible solutions exist today that cansignificantly improve care. Whilemore advanced technologies in thefuture hold great promise, given thedemonstrated and potential ben-efits for the laboratory, pharmacy,clinician, and patient, the case forimmediate efforts to link labora-tory and pharmacy information iscompelling.

Table 2. Labeled Laboratory-Pharmacy Interactions*

Laboratory Result

Top 40 Drugs New Drugs (n = 37)

TotalWarnings

No. of DrugsWith Warning

TotalWarnings

No. of DrugsWith Warning

Contraindication for drug 11 9 20 14Indication for drug 7 7 3 3Dose adjustment 40 31 28 23Indicating toxicity 169 39 161 32Baseline monitoring 16 11 12 8Follow-up monitoring 20 11 16 10Interfered with by drug 5 3 2 2Total 268 40 242 37

*As listed in the 2000 Physicians’ Desk Reference.97 Official Food and Drug Administration labeling fororal dosage medications was evaluated. Top 40 drugs were based on 2000 IMS data. New drugs werebased on new molecular entities newly approved by the Food and Drug Administration and marketed in1999 and 2000.




Accepted for publication August 1,2002.

This study was supported in partby grant 11552 from the Agency forHealthcare Research and Quality, De-velopmental Centers for Research inPatient Safety Initiative, Rockville, Md.

Corresponding author and re-prints: Gordon D. Schiff, MD, Depart-ment of Medicine, Cook County Hos-pital, 1900 W Polk St, Room 901-AX,Chicago, IL 60612 (e-mail: [email protected]).

REFERENCES

1. Schiff GD, Aggarwal HC, Kumar S, McNutt RA.Prescribing potassium despite hyperkalemia:medication errors uncovered by linking labora-tory and pharmacy information systems. Am JMed. 2000;109:494-497.

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