American Journal of Hematology 3: 127-135 (1977)
A Computer Program for the Diagnosis of Hematologic Disorders Paul R. Reich, Daniel E. Geer, Jr., and Howard L. Bleich Thorndike Laboratory and the Department of Medicine, Harvard Medical School and the Beth Israel Hospital, Boston, Massachusetts
A computer program has been developed to assist medical personnel in the diagnosis of hematologic disorders. The program requests information such as the patient's hematocrit, white blood-cell count, platelet count, and selected physical findings. Major problems are identified, and the program then requests further information as needed to determine whether the patient has I or more of 174 hematologic disorders. An evaluation note is then printed that summarizes the most important hematologic data and includes a list of selected hematologic diagnoses, a discussion of why each diagnosis is listed, a description of its pathophysiology and information concerning etiology and treatment. The printout concludes with pertinent references to the medical literature. When the program was tested with 135 patients referred for hematologic consultation, diagnoses produced by the program were in complete agreement with the hematologist in 87 cases, in partial agreement in 23 cases and not in agreement in 2S cases. The program was also tested with 34 hematologic cases from the New England Journal of Medicine's Clinical-Pathological Conferences. In 24 patients, the computer and anatomic diagnoses were in complete or partial agreement, and in 10 they disagreed. Anecdotal evidence suggests that explanations of pathophysiology contained in the evaluation notes may be useful to students. It is concluded that the program could be useful as a memory aid for the practitioner and as a teaching aid for the student. Key words: computer, treatment, evaluation, diagnosis, hematology
INTRODUCTION
Computer technology has been used to collect patient histories (1); to interpret electrocardiograms (2,3); and to assist in the diagnosis and management of acid-base (4,5), electrolyte (6), respiratory (7), surgical (8), dermatologic (9, 10), and thyroid (11) disorders. In the field of hematology, the pioneering efforts of Upkin and coworkers served as a model for early work in computer-assisted diagnosis (12). Subsequently, Bishop Received April 4, 1971; accepted May 20, 1971. Address reprint requests to Dr. Paul R. Reich, Beth Israel Hospital, 330 Brookline Avenue Boston. MA 0221S.
127
'
© 1917 Alan R. Liss, Inc., 150 Fifth Avenue, New York, NY 10011
,
128
Reich. Geer, and Bleich
and Warner developed a program for the diagnosis of polycythemic disorders, a program that provided the first example of the use of Bayes' theorem with continuous variables (13). More recently, Engle and coworkers have described an interactive computer program in which the user types numbers corresponding to symptoms, physical findings, or range of laboratory values, and the program computes the probability of 1 or more of 40 hematologic diagnoses (14, 15). This program also uses a variation of Bayes' theorem to translate the patient's symptoms, physical findings, and laboratory results into a list of diagnoses. Our methods differ in that we chose to write specific decision rules for each of the 174 hematologic diagnoses considered by our program. This strategy permits the program to use known principles of pathophysiology that are omitted in a program based on Bayes' theorem. In addition, the availability of MUMPS, an interpretive computer language that facilitates the manipulation of English text, has made it possible for the computer program to accept descriptive input from the user; it is no longer necessary to look up signs and symptoms in a table and type in corresponding numbers (16). TIle result is an interactive computer program that communicates with the user by means of a teletypewriter or cathode-ray tube terminal. The program directs a dialogue during which the user provides pertinent clinical and laboratory information and receives, in return, a discussion of the pathophysiology leading to each diagnostic conclusion, a list of additional laboratory tests that merit consideration, suggestions for therapy, and a short list of references to the litera t ure. METHODS
The program is written for a PDP-IS computer (Digital Equipment Corporation, Maynard, Mass.) and may be called from a suitable terminal connected to the Bell Telephone System. The computer can service up to 24 teletype or cathode-ray tube terminals Simultaneously and respond to each terminal almost instantaneously. Each diagnosis considered by the program is associated with a series of criteria that include or exclude it. For the anemias, multiple sets of criteria define the confidence with which each diagnosis is made. A flow diagram depicting a portion of the branching logic is shown in Fig. 1. After initial questions are asked, control of the program passes to sections dealing with polycythemia or anemia, leukocytosis or leukopenia, thrombocytosis or thrombopenia and bleeding disorders. The logic flow and criteria used for megaloblastic anemia are shown in Fig. 2. The major clinical features of megaloblastic anemia are considered in items 1-6. The number of items present determines the degree of confidence with which the diagnosis is considered. If 1 or more of these features are present, items 7-12 are requested. TIle degree of confidence is increased if the responses to the questions indicate that additional characteristics of megaloblastic anemia are present. All the information available to the program is then used to define the cause of the megaloblastic anemia. Every cause cannot be considered, since too many entries would be needed, but the discussion provided, once a categorization is made, includes a list of potential causes. All the causes of folic acid deficiency, for example, are listed in the note accompanying the diagnosis of megaloblastic anemia secondary to folic acid deficiency. The program rules out diagnoses for which there is strong evidence but which are contradicted by one of the findings: even if the Schilling Part I is abnormal, the presence of gastric acid would rule out pernicious anemia. The program consists of computer instructions and English text. The instructions
Computerized Hematologic Diagnosis
129
PATIENT DATA (History, PhYSical Examlnahon, Laboratory Dato)
I
A"O.: Chi7 '"':"_, I
I i i
I
~=:,
openoo
ApI~1O ~IS~
etc
I
Apiosoo Drug HypersplenISm
I
I Other Hematolog ic Diseases
Infection Neutropluha Lymphocytosis EoslO. etc
ThromblnFibrinogen
Foetors
I Thrombocytosis
Primary SecOlldary Relative
I
ITP DIC etc
Coog
Platelets
I
~UkoCytosiS
Polycremio
Anticoag etc
Bleeding Tumor Myeloprol Splenectomy Syndrome
etc
rl-------,,-------rt-----.,------T,-------r--------T,------~I HypochromiC
II
I
MegaloblastIC HemolytiC I
I
I
lrO
A Computer Program for the Diagnosis of Hematologic Disorders Paul R. Reich, Daniel E. Geer, Jr., and Howard L. Bleich Thorndike Laboratory and the Department of Medicine, Harvard Medical School and the Beth Israel Hospital, Boston, Massachusetts
A computer program has been developed to assist medical personnel in the diagnosis of hematologic disorders. The program requests information such as the patient's hematocrit, white blood-cell count, platelet count, and selected physical findings. Major problems are identified, and the program then requests further information as needed to determine whether the patient has I or more of 174 hematologic disorders. An evaluation note is then printed that summarizes the most important hematologic data and includes a list of selected hematologic diagnoses, a discussion of why each diagnosis is listed, a description of its pathophysiology and information concerning etiology and treatment. The printout concludes with pertinent references to the medical literature. When the program was tested with 135 patients referred for hematologic consultation, diagnoses produced by the program were in complete agreement with the hematologist in 87 cases, in partial agreement in 23 cases and not in agreement in 2S cases. The program was also tested with 34 hematologic cases from the New England Journal of Medicine's Clinical-Pathological Conferences. In 24 patients, the computer and anatomic diagnoses were in complete or partial agreement, and in 10 they disagreed. Anecdotal evidence suggests that explanations of pathophysiology contained in the evaluation notes may be useful to students. It is concluded that the program could be useful as a memory aid for the practitioner and as a teaching aid for the student. Key words: computer, treatment, evaluation, diagnosis, hematology
INTRODUCTION
Computer technology has been used to collect patient histories (1); to interpret electrocardiograms (2,3); and to assist in the diagnosis and management of acid-base (4,5), electrolyte (6), respiratory (7), surgical (8), dermatologic (9, 10), and thyroid (11) disorders. In the field of hematology, the pioneering efforts of Upkin and coworkers served as a model for early work in computer-assisted diagnosis (12). Subsequently, Bishop Received April 4, 1971; accepted May 20, 1971. Address reprint requests to Dr. Paul R. Reich, Beth Israel Hospital, 330 Brookline Avenue Boston. MA 0221S.
127
'
© 1917 Alan R. Liss, Inc., 150 Fifth Avenue, New York, NY 10011
,
128
Reich. Geer, and Bleich
and Warner developed a program for the diagnosis of polycythemic disorders, a program that provided the first example of the use of Bayes' theorem with continuous variables (13). More recently, Engle and coworkers have described an interactive computer program in which the user types numbers corresponding to symptoms, physical findings, or range of laboratory values, and the program computes the probability of 1 or more of 40 hematologic diagnoses (14, 15). This program also uses a variation of Bayes' theorem to translate the patient's symptoms, physical findings, and laboratory results into a list of diagnoses. Our methods differ in that we chose to write specific decision rules for each of the 174 hematologic diagnoses considered by our program. This strategy permits the program to use known principles of pathophysiology that are omitted in a program based on Bayes' theorem. In addition, the availability of MUMPS, an interpretive computer language that facilitates the manipulation of English text, has made it possible for the computer program to accept descriptive input from the user; it is no longer necessary to look up signs and symptoms in a table and type in corresponding numbers (16). TIle result is an interactive computer program that communicates with the user by means of a teletypewriter or cathode-ray tube terminal. The program directs a dialogue during which the user provides pertinent clinical and laboratory information and receives, in return, a discussion of the pathophysiology leading to each diagnostic conclusion, a list of additional laboratory tests that merit consideration, suggestions for therapy, and a short list of references to the litera t ure. METHODS
The program is written for a PDP-IS computer (Digital Equipment Corporation, Maynard, Mass.) and may be called from a suitable terminal connected to the Bell Telephone System. The computer can service up to 24 teletype or cathode-ray tube terminals Simultaneously and respond to each terminal almost instantaneously. Each diagnosis considered by the program is associated with a series of criteria that include or exclude it. For the anemias, multiple sets of criteria define the confidence with which each diagnosis is made. A flow diagram depicting a portion of the branching logic is shown in Fig. 1. After initial questions are asked, control of the program passes to sections dealing with polycythemia or anemia, leukocytosis or leukopenia, thrombocytosis or thrombopenia and bleeding disorders. The logic flow and criteria used for megaloblastic anemia are shown in Fig. 2. The major clinical features of megaloblastic anemia are considered in items 1-6. The number of items present determines the degree of confidence with which the diagnosis is considered. If 1 or more of these features are present, items 7-12 are requested. TIle degree of confidence is increased if the responses to the questions indicate that additional characteristics of megaloblastic anemia are present. All the information available to the program is then used to define the cause of the megaloblastic anemia. Every cause cannot be considered, since too many entries would be needed, but the discussion provided, once a categorization is made, includes a list of potential causes. All the causes of folic acid deficiency, for example, are listed in the note accompanying the diagnosis of megaloblastic anemia secondary to folic acid deficiency. The program rules out diagnoses for which there is strong evidence but which are contradicted by one of the findings: even if the Schilling Part I is abnormal, the presence of gastric acid would rule out pernicious anemia. The program consists of computer instructions and English text. The instructions
Computerized Hematologic Diagnosis
129
PATIENT DATA (History, PhYSical Examlnahon, Laboratory Dato)
I
A"O.: Chi7 '"':"_, I
I i i
I
~=:,
openoo
ApI~1O ~IS~
etc
I
Apiosoo Drug HypersplenISm
I
I Other Hematolog ic Diseases
Infection Neutropluha Lymphocytosis EoslO. etc
ThromblnFibrinogen
Foetors
I Thrombocytosis
Primary SecOlldary Relative
I
ITP DIC etc
Coog
Platelets
I
~UkoCytosiS
Polycremio
Anticoag etc
Bleeding Tumor Myeloprol Splenectomy Syndrome
etc
rl-------,,-------rt-----.,------T,-------r--------T,------~I HypochromiC
II
I
MegaloblastIC HemolytiC I
I
I
lrO
