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Oesophageal pH monitoring made easy
As many as 44% of adult Americans complain of heartburn at least once a month and 13% take indigestion tablets at least twice a week, according to a poll in the USA. Most never consult a doctor, but almost all probably suffer some degree of gastro-oesophageal reflux disease (GORD).

GORD is generally not difficult to diagnose, and simple advice on weight loss, smoking, alcohol, diet and posture takes care of most sufferers. A small proportion, but significant number, have atypical symptoms of angina-like chest pain, globus, hoarseness or atypical asthma. The diagnosis of GORD is aided in these patients by using 24-hour ambulatory oesophageal pH monitoring.

Equipment is now becoming available that makes this possible on an outpatient or GP basis. Though not cheap at about £4000 with £30 consumables each test, the equipment and associated computer programs are simple to use, and costs per patient test are less than traditional methods of diagnosis as well as having better diagnostic specificity. An antimony 2.3 mm catheter is calibrated, followed by nasogastric insertion as far as the stomach - detected by a sharp drop in pH. It is then pulled back to be some 5 cm above the lower oesophageal sphincter.

The small data logger records the oesophageal pH at several positions over 24 hours. An event button is pressed by the patient when symptoms occur, and a diary is kept of eating and activities. By hooking up the data logger to a computer a virtually instantaneous picture of oesophageal relating symptoms to oesophageal pH is obtained.

A number of studies confirm that 24-hour oesophageal pH monitoring is the best diagnostic tool available. Hospital research is continuing, but there is a dearth of RCTs, and no studies in the GP setting to indicate whether this approach can deliver benefits in care or cost.

References:

  1. Owen et al, Hospital Update, January 1993.
  2. Caestecker & Heading, Editorial, European Journal of Gastroenterology & Hepatology, 1991, 3: 285-287.
  3. Hewson et al, American Journal of Medicine, 1991, 90, 576-583.
Further information on equipment:

John Giddings, Oakfield Instruments, Eynsham, Oxford, OX8 1JA.

Questions to be Answered

Q: What need is met by this test?
A: Differential diagnosis of chest pain.
Q: What happens at present?
A: A proportion of people with chest pain have cardiac disease excluded but have no specific cause identified. Reflux of gastric acid is a cause of such pain. Present tests for this cause are of low sensitivity.
Q: Is quality improved?
A: Sensitivity is increased.
Q: What is the capital cost?
A: About £4000.
Q: What is the revenue cost?
A: About £30 per case.
Q: What is the likely cost per million population?
A: No general estimate because of different clinical policies.
Q: Will this increase or decrease the total cost of secondary care?
A: Diagnosis will be reached more quickly. This will reduce costs in those cases. None of the papers gives adequate cost analysis.
Q: What is the effect on the total cost (primary + secondary)?
A: Will have little effect on primary care costs.

Advice to Purchasers

  • will increase quality or effectiveness
  • cost neutral if other tests done less often
  • worth considering including in specification if no increase in investigating non-cardiac chest pain

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