Objective: To understand how practice guidelines are used in malpracti
ce litigation. Design: Review of the open and closed malpractice claim
s of two medical malpractice insurance companies, and a mailed survey
of attorneys who litigate malpractice claims. Setting: United States.
Participants. Two insurance companies and 960 randomly selected malpra
ctice attorneys. Measurements: Frequency and nature of the use of prac
tice guidelines in litigation; understanding and frequency of the use
of practice guidelines by attorneys in malpractice cases. Results: 259
claims opened in 1990-1992 at two insurance companies, including all
obstetrics and anesthesia claims and a random sample of other claims,
were reviewed. Seventeen of these claims involved practice guidelines,
which were used as exculpatory evidence (exonerating the defendant ph
ysician) in 4 cases and as inculpatory evidence (implicating the defen
dant physician) in 12 cases. The only physician or patient factors ass
ociated with use of a guideline was a longer physician-patient relatio
nship (P = 0.021). Nine hundred and sixty surveys were mailed and 578
were returned (response rate, 60.1%). Attorneys reported that once a s
uit is initiated, practice guidelines are likely to be used for inculp
atory purposes (inculpatory in 54% of cases; exculpatory in 22.7% of c
ases). However, guidelines that seem to offer exculpatory value induce
attorneys not to bring suits. The only attorney factor associated wit
h increased use of guidelines was a practice in which more than 50% of
business was in medical malpractice. Conclusions: Guidelines are used
both by plaintiffs' and defendants' attorneys in malpractice cases. T
he emphasis in health reform proposals on guidelines as exculpatory ev
idence should be carefully considered.