Glenn Edwards

Peirs: A pathologist-maintained expert system for the interpretation of chemical pathology reports

Summary Provision of a comprehensive interpretative service is an important challenge facing chemical pathologists. Attempts to automate report interpretation using expert systems have been limited in the past by the difficulties of rule base maintenance. We have applied a novel knowledge acquisition technique, ripple down rules, in the development of PEIRS (Pathology Expert Interpretative Reporting System), a user‐maintained expert system for automating chemical pathology report interpretation. We created over 950 rules for thyroid function tests, arterial blood gases and other test sub‐groups in 9 mths of operation. A staff pathologist performed all maintenance tasks as part of his routine duties without any need for computer programming skills. No clerical staff involvement was required. Duplication of rule addition for reports requiring multiple comments was the only limitation to coverage of other high volume test groups. PEIRS is the first expert system for the automated interpretation of a range of chemical pathology reports which operates in routine use without extra staffing requirements. PEIRS does not require “knowledge engineering” expertise. Thus, the knowledge base is flexible and can be easily maintained and updated by the pathologist. Expert systems based on ripple down rules should enable pathologists to provide a comprehensive automated interpretative service within the context of the total testing process.

Laboratory Diagnosis of Phaeochromocytoma: Which Analytes Should We Measure?

There is a diversity of advice in the literature as to which biochemical assays are best suited to the investigation of patients with a suspected phaeochromocytoma. The challenge for the clinical laboratory is to select those assays which detect all phaeochromocytomas, whilst having the lowest incidence of false positive diagnoses. We compared the sensitivity and specificity of a wide range of assays currently used for the biochemical diagnosis of phaeochromocytoma using either specific gas chromatographic-mass spectrometric (GC/MS) or high performance liquid chromatography-electrochemical detection (HPLC/ED) techniques. Noradrenaline (NA), adrenaline (ADR), dopamine (DA), 3,4-dihydroxyphenylglycol (DHPG), hydroxymethoxymandelic acid (HMMA), normetanephrine (NMET) and metanephrine (MET) were measured in 24 h urine specimens from 20 patients with histologically proven phaeochromocytoma and a large group of patients referred for investigation but subsequently found not to have a phaeochromocytoma. Because phaeochromocytomas are a heterogeneous group of hormone secreting tumours, no single analyte could achieve 100% sensitivity; 100% sensitivity was achieved only when the combination of both NA and ADR or NMET and MET was used. DA, DHPG and HMMA all had poor sensitivities. HMMA had a sensitivity of 70% when using the upper 95% confidence level (48μmol/24 h) of the non-tumour patients as the cut-off. By lowering the cut-off to 35μmol/24 h the sensitivity could be increased to 100% but at the expense of the specificity which was decreased from 98 to 92%. On the basis of this study we recommend the specific measurement of either NA and ADR or NMET and MET as the most suitable analytes for the detection of phaeochromocytoma, and further that, due to its poor specificity, HMMA be abandoned as a suitable analyte.

Experience with Ripple-Down Rules

Abstract Ripple-Down Rules (RDR) is an approach to building knowledge-based systems (KBS) incrementally, while the KBS is in routine use. Domain experts build rules as a minor extension to their normal duties, and are able to keep refining rules as KBS requirements evolve. Commercial RDR systems are now used routinely in some Chemical Pathology laboratories to provide interpretative comments to assist clinicians make the best use of laboratory reports. This paper presents usage data from one laboratory where, over a 29 month period, over 16,000 rules were added and 6,000,000 cases interpreted. The clearest evidence that this facility is highly valuable to the laboratory is the on-going addition of new knowledge bases and refinement of existing knowledge bases by the chemical pathologists.

Opportunistic screening for familial hypercholesterolaemia via a community laboratory

Background Familial hypercholesterolaemia (FH) is an inherited disorder characterized by increased serum low-density lipoprotein (LDL)-cholesterol concentrations and premature atherosclerotic cardiovascular disease. The majority of people with FH are currently undiagnosed. We sought to determine the ability of a community laboratory to screen for individuals with potential FH. Methods Serum LDL-cholesterol concentrations issued by a private community laboratory in Western Australia were reviewed over a one-year period (1 May 2010 to 31 April 2011). We assessed the prevalence of possible FH based on LDL-cholesterol thresholds employed by the Make Early Diagnosis-Prevent Early Death (MED-PED), the Simon Broome Registry and the Dutch Lipid Clinic Network criteria. Results During this period, 84,823 people had 99,467 serum LDL-cholesterol measurements, with 91.8% requested by general practitioners. A secondary cause of hypercholesterolaemia was identified in 8.3% of subjects with an LDL-cholesterol ≥5.0 mmol/L. The prevalence of FH based on an LDL-cholesterol ≥6.5 mmol/L, the 99.75th percentile, was 1:398 in this sample population; similarly, the MED-PED LDL-cholesterol criteria gave a prevalence of 1:482. Conclusions The community laboratory is well placed to screen opportunistically for subjects with potential FH. This may be achieved using either the MED-PED criteria or a serum LDL-cholesterol cut-off point of ≥6.5 mmol/L, irrespective of age. Further investigation is required to determine the most effective method of identifying these individuals and, thereby, ensuring referral to a specialist lipid clinic.

Screening for familial hypercholesterolaemia

Summary Familial hypercholesterolaemia (FH) is an autosomal dominant disorder characterised by increased plasma concentrations of low density lipoprotein (LDL) cholesterol leading to atherosclerosis and premature coronary heart disease (CHD) and death. The clinical diagnosis of FH is based on a personal and family history, physical examination findings and LDL-cholesterol concentrations. FH is primarily caused by mutations in the LDL-receptor gene (LDLR), and less frequently by mutations in genes for APOB and the more recently identified PCSK9. Lifestyle modification and pharmacotherapy can delay or prevent the onset of CHD in FH. It is estimated that only 20% of cases have been diagnosed in Australia and that the majority are inadequately treated. Screening options for FH include population screening (of children or adults), targeted screening of patients with premature CHD and their relatives, or opportunistic screening such as flagging laboratory lipid reports. Cascade screening, a form of targeted screening, is an ethically acceptable, cost-effective strategy for the identification of FH. However, for screening to be successful, medical practitioners need to be aware of the signs and diagnosis of FH and the benefits of early treatment.

Impact of interpretative commenting on lipid profiles in people at high risk of familial hypercholesterolaemia

BACKGROUND Familial hypercholesterolaemia (FH) is an autosomal dominant condition characterised by increased low density lipoprotein cholesterol (LDL-c), xanthomata and premature cardiovascular disease. However, it is currently underdiagnosed and undertreated in Australasia. We sought to investigate whether interpretative commenting on lipid profiles could improve FH detection and treatment. METHODS A case-historical control study of individuals with serum LDL-c concentrations ≥6.5 mmol/L; 96 cases receiving an interpretative comment suggesting FH compared with 100 controls not receiving a comment. RESULTS Serum LDL-c was repeated in 63 (66%) cases and 70 (70%) controls within 12 months. LDL-c decreased in 59 (94%) cases and in 61 (87%) controls. In individuals with a repeat LDL-c, a mean LDL-c reduction of 2.3 mmol/L (32%; p<0.0001) was demonstrated in controls, compared with 3.0 mmol/L (42%; p<0.0001) in cases; significantly greater than that of controls (p<0.005). Interpretative comments suggesting specialist review were associated with a higher referral rate compared with controls (11.5% vs 1%, p<0.05). CONCLUSION Interpretative commenting was associated with a significant additional LDL-c reduction and increased specialist referrals compared with controls. However, only a minority of individuals received a specialist referral. Interpretative commenting may play an important role in the detection and management of FH.

Screening for lipid disorders

Summary Lipid disorders, also known as dyslipidaemias, are abnormalities of lipoprotein metabolism and include elevations of total cholesterol, low density lipoprotein (LDL) cholesterol, and triglyceride, and reductions in high density lipoprotein (HDL) cholesterol, and can be acquired or familial in nature. Dyslipidaemia is a major risk factor for coronary heart disease and cardiovascular disease (CVD), which is the leading cause of morbidity and mortality in Australia. Dyslipidaemia is defined by laboratory testing and using statistically determined criteria. Although the benefits of detecting and treating dyslipidaemia in patients with known CVD is clear, controversy remains regarding screening asymptomatic individuals who are not known to be at increased cardiovascular risk. This review examines the role of screening in the detection and treatment of individuals with lipid disorders.

A pathologist hitchhiker's guide to informatics

The contemporary practice of pathology is heavily reliant upon information systems. These systems are becoming increasingly sophisticated and College Fellows are frequently required to have input on their design, selection, implementation and evaluation. Laboratories are adopting decision support technologies to support workflow management and clinical interpretation of pathology tests. The computationally intensive field of bioinformatics is growing rapidly especially in genomics laboratories while statistics, another informatics discipline, has always been an important part of Fellowship training. College Fellows have a professional duty of care, and also carry ethical and medico-legal responsibility, for the efficacy, reliability, safety and security of such systems. Significantly, the development of Health Informatics also proceeds apace in the wider medical community. Data mining tools, social media and decision support are expected to improve health resource utilisation, evidence-based practice, and clinical effectiveness. These tools will also become widely deployed as patients and health consumers have more control over health service delivery and expect an improved experience in their contact with the health system.