Table 2.

Process of diagnostic decision-making in general practice using Isabel

Clinical category	Features entered into clinical record	Features entered into Isabel	Differential diagnosis (Isabel)	Action	Diagnosis (identified by Isabel?)
Abdominal	N/A	Right hypocondrium abdominal pain, tiredness	Ischaemic heart disease, non-Hodgkin's lymphoma, neoplasms of the kidney, CMV colitis, colorectal cancer, Whipple disease, pancreatic neoplasms, adrenal neoplasms, endocarditis, inflammatory bowel disease	N/A	N/A
		Right abdominal pain, tiredness, bursting	Whipple disease, mycotic aneurysm, diphtheria, HIV/AIDS, depression, pemphigus, acute appendicitis, non-Hodgkin's lymphoma, thoracolumbar spinal injuries, multiple sclerosis
		Right hyperconial abdominal pain, tiredness	Ischaemic heart disease, non-Hodgkin's lymphoma, neoplasms of the Kidney, CMV colitis, colorectal cancer, Whipple disease, pancreatic neoplasms, adrenal neoplasms, endocarditis, inflammatory bowel disease
CVS	Swelling of legs, bilateral	Bilateral leg swelling, overweight	Hypothyroidism, sleep apnea, Cushing's syndrome, ischaemic heart disease, pulmonary thromboembolism, SLE, chronic venous insufficiency, deep vein thrombosis, glomerulonephritis, myocarditis	FBC, U&E, LFT, ESR, CRP	Iatrogenic due to calcium channel blocker drugs (No)
		Bilateral leg swelling, overweight, rheumatoid arthritis	Endocarditis, pericarditis, intestinal bypass arthritis, hypothyroidism, Cushing's syndrome, neutrophilic dermatoses, sleep apnea, palindromic rheumatism, SLE, coccidiodomycosis
Endocrine	Tiredness, poor appetite, feels hot and cold	Fatigue, anorexia, weight increase, forgetfulness	Urinary tract infection, bipolar disorders, depression, diabetic nephropathy, glomerulonephritis, hypothyroidism, ovarian neoplasms, paraneoplastic neurological syndrome, renal failure, COPD	TFT, thyroid antibodies LFT, FBC, CRP, blood glucose, antinuclear factor, PHQ9	Hypothyroid (Yes)
Gastro-intestinal	Epigastric pain, dizzy, relief with alginate	Jaw pain, heartburn, epigastric discomfort	Ischaemic heart disease, hypothyroidism, aortic aneurysm/dissection, gastroesophageal reflux, peptic ulcer disease, pancreatic neoplasms, optic neuropathy, acute visual loss, facial injury/fractures, trigeminal nerve disorders	ECG gastroscopy	Oesophagitis (Yes)
Musculoskeletal	Foot pain, bilateral, dorsal	Foot pain, bilateral, dorsal, recent	Charcot's joint, CNS TB & TB meningitis, cellulitis, diabetic lower limb disease, diabetic neuropathy, endocarditis, flatfoot disorders, foot fractures, metatarsal fractures, morton neuroma	Referral	Osteoarthritis (No)
	Fatigue, dizziness, generalized paraesthesia, headache	Numbness, headache, tired	Migraine, transient ischaemic attack, Lyme disease, herpes zoster, megaloblastic anemias, head injury, interstitial nephritis, iron deficiency anaemia, lymphoma, multiple sclerosis	FBC, U&E, LFT, TFT, blood glucose, bone profile, B12, folate	OA spine? Vertical collapse? (No)
	Neck pain, off balance	Neck pain, dizziness	Arterial aneurysms/dissection, atlantoaxial instability, cervical spondylosis, migraine, brain neoplasms, atlantoaxial dislocation, bacterial meningitis, bartonella infection, cerebral sinus venous thrombosis, cervical plexopathy	None	Cervical spondylitis (Yes)
	Leg pain	Leg pain, limping	Megaloblastic anaemias, Factor V Leiden, leukaemia, meningococcal disease, arachnoid cysts, autoimmune hemolytic anemias, femoral fractures, intervertebral disk herniation, malignant bone tumours, Marfan syndrome	Referral	N/S
	n/a	Hip pain, limping	Hip arthritis, pelvic injuries, fractures of the hip, avascular necrosis of the femoral head, coccygeal fractures, herpes zoster, hip dislocation, hip trauma, ilopsoas bursitis, sickle cell disease/crisis	N/A	N/A
Neurological	Headache, worse on coughing	Headache, numbness	Transient ischaemic attack, Lyme disease, migraine, polyneuropathy disorders, arachnoid cysts, megaloblastic anaemias, adrenal neoplasms, head injury, lymphoma, brain neoplasms	Emergency admission	Subarachnoid haemorrhage? (No)
Non-specific	Abnormal weight loss	Weight loss	Neoplasms of the kidney, lung abscess, pancreatic neoplasms, non-Hodgkin's lymphoma, Whipple disease, gastritis, urinary tract infection, Hodgkin's disease, adrenal neoplasms, hyperthyroidism	PSA, FOBT	Anxiety? (No)
	Raised temperature, intermittent	Temperature control, Parkinson's disease, swings	Urinary tract infection, Alzheimer's disease, non-Hodgkin's lymphoma, Parkinson's disease, progressive supranuclear palsy, borderline personality disorder, bacterial meningitis, bipolar disorders, CNS TB & TB meningitis, candidal infection	FBC, CRP, TFT	N/S
	Mass in groin, pain	Swelling groin, painful, groin lump	Genital herpes, genital ulcer syndrome, arterial aneurysms/dissection, Haemophilus ducreyi infection, syphilis, lipoma, lymphoma, proctitis, biliary pain, colorectal cancer	Referral	Abscess (No)
		Lump, painful	Uterine neoplasms, pulmonary thromboembolism, benign bone tumours, neutrophilic dermatoses, psychosomatic illness, soft tissue neoplasms, epidermoid cyst, head and neck neoplasms, oral cancer, peritonsillar abscess/quinsy
		Lump, painful, groin lump	Uterine neoplasms, pulmonary thromboembolism, benign bone tumours, neutrophilic dermatoses, psychosomatic illness, soft tissue neoplasms, epidermoid cyst, head and neck neoplasms, oral cancer, peritonsillar abscess/quinsy
Respiratory	Oesophegeal spasm, cough, throat tightening	Chest discomfort, spasmodic, spasm, globus	Ischaemic heart disease, dystonia disorders, Sturge–Weber disease, lung neoplasms, esophageal neoplasms, progressive supranuclear palsy, pulmonary thromboembolism, supraventricular tachycardia, adult-onset basal ganglia disease, anthrax	C×R	COPD (No)
	Dyspnoea cough	Breathlessness	Iron deficiency anemia, sarcoidosis, ARDS, heart failure/CHF, ischaemic heart disease, asthma, myocarditis, pulmonary AV fistula, aspiration syndromes, pericardial effusion/tamponade	FBC	Asthma (known) (Yes)
Skin	Intermittent, erythema of lower limbs	Raynauds, redness skin, intermittent, erythema	Dermatomyositis/polymyositis, paronychial inflammation of the nail, autoimmune hepatitis, testicular torsion, parvoviral infections, gonococcal infection, Lyme disease, urticaria/angioedema, allergic rhinitis, intestinal fistulas and abscesses	Discussed with immunologist	N/S

FBC, full blood count; LFT, liver function test; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; ECG, electrocardiogram; SLE, systemic lupus erythematosus; PSA, prostate-specific antigen; COPD, chronic obstructive pulmonary disease; FOBT, fecal occult blood test

N/S Not stated in clinical record; N/A Clinical record not made available