Primary care access to computed tomography for chronic headache

INTRODUCTION

Headache is one of the most common symptoms encountered in general practice, with an annual consultation rate of 4.44 per 100 registered patients.1 It is the single most common cause for neurology referral in the UK,2 accounting for up to 22% of GP referrals to neurologists.3 Chronic tension-type headache and migraine are the two most common headache types encountered in the UK population, both in primary care4 and specialist clinics.5 It has been argued that most primary headache can be managed in primary care, and that investigations are rarely needed.6 However, healthcare professionals often find the diagnosis and classification of headache difficult,7 and both healthcare professionals and patients worry about serious causes such as brain tumours.8

The role of imaging in this situation has been extensively reviewed, and guidance has been published for risk which stratifies patients according to presentation.9^,10 Although pathology may be excluded by neuroimaging, the diagnostic yield is low,9^,11^,12 and the duration of reassurance for patients is short.13 Moreoever, there is a risk of finding coincidental abnormalities that may generate more anxiety.14 So, the US Headache Consortium Guidelines6 and the Scottish Intercollegiate Guidelines Network8 do not recommend neuroimaging for chronic headache in the absence of focal neurological signs. Nevertheless, observational studies indicate that brain scans are widely carried out on patients with normal neurological examinations.15^–18

In a randomised trial to examine the effect of scanning of patients with chronic daily headache, referral rates to the neurology service were reduced from 17/74 (23%) in the control group to 1/76 (1.3%) in the scanned group.13 Although this study was restricted to selected patients referred to a trial, it raises the possibility that provision of an open access service might reduce chronic headache referral rates to secondary care for the entire population. Open access services have been shown to influence the management of patients in primary care by helping to avoid referrals to secondary care, ensuring referral to the appropriate specialty, and speeding up the time to diagnosis with a consultant opinion.19^–21

The aim of this study was to estimate both the rate of referral of patients with chronic headache to an open access CT service, and the effect on referral rates to the neurology service in a defined population.

METHOD

The study was performed in Tayside and North East Fife, Scotland. The adult population of 421 20722 is cared for by 309 GPs in 72 GP practices, and four full-time consultant neurologists, working in the local university teaching hospital, with outreach clinics in two district hospitals. Care is free at the point of access and few patients seek care outside the area.

The number of consultations for headache was estimated by applying the UK rate1 to the Tayside and North East Fife population, and the scan referral rate was the number of scan referrals as a proportion of this estimate.

All of the GPs were given access to refer patients directly to brain CT at three sites in the study area: Ninewells Hospital, Dundee; Perth Royal Infirmary, Perth; and Stracathro Hospital, Angus. Between these hospitals, approximately 7000 CT brain scans are carried out routinely each year. The referral protocol stated that patients should be aged 18 years or more, with a normal neurological examination, and symptoms consistent with chronic, unchanging headache, or of a non-acute nature such that secondary care referral for specialist opinion was not deemed necessary. The duration of headache was not specified.

All referrals were analysed prospectively for a 12-month period from 1 April 2005 to 31 March 2006, and data were collected on the referral and referring practitioner and radiological findings. A follow-up questionnaire was sent to the referring GP with the CT scan report to establish whether the CT service had resulted in or stopped a referral to neurologists. The Tayside outpatient clinic database was used to determine which of the scanned patients were referred to a neurology clinic between 1 April 2005 and 31 March 2007, giving a follow-up period of at least 1 year after each patient's scan. GP referral letters and hospital records were then assessed, so that only those patients who were referred because of headache were included.

RESULTS

Between 1 April 2005 and 31 March 2006 the GPs in the study area referred 232 patients for brain CT (55.1/100 000/year, 95% confidence interval [CI] = 50.4 to 59.9). There were an estimated 18 702 headache consultations, and the referral rate to the open access service was 1.24%. A scan was not performed for 17 (7.3%) of the patients because six appointments were cancelled, five patients did not attend, two request forms were incomplete, and four requests were declined because the radiologist did not think that the referrals complied with study criteria (one for memory loss, one for personality change, one for suspected stroke, and one for suspected transient ischaemic attack). So 215 (92.7%) of the referred patients were scanned (51.0/100 000/year, 95% CI = 46.3 to 55.8), and two patients were recalled for second scans. Table 1 gives details of the age and sex of the 215 scanned patients, grouped according to whether or not they were referred to neurology clinic for chronic headache. The age range of the study population was 20–85 years.

The CT scans of 215 patients identified three lesions which, in the opinion of the study neurologists, might have caused chronic headache. One patient had metastatic lung cancer, another patient had a meningioma, and a third patient had an arteriovenous malformation. It was concluded that 22 patients had non-significant findings including old infarcts (n = 7), other ischaemic changes (n = 7), arachnoid cysts (n = 2), sinusitis (n = 2), pineal cyst (n = 1), prominent deep cerebral vein (n = 1), probable artefact (n = 1), and other unspecified changes (n = 1), giving a 1.4% yield for significant pathological findings and 10.2% for non-significant findings; 190 (88.4%) CT scans were reported to be normal.

The open access service was used by 140 (45%) of 309 Tayside GPs from 59 (82%) of the 72 GP practices. The highest number of CT requests from a single GP was seven: most GPs referred one patient. Completed questionnaires were obtained from 189 (88%) of the referring GPs, and the responders reported that, in 167 (88%) of 189 cases with completed questionnaires, the scan had stopped a referral to secondary care; in 10 (5%) cases the scan had caused a referral, and in 12 (6%) cases a referral had been made to neurology service at the same time as the scan request.

There were 288.9 patient years of follow-up in 215 patients, giving a mean follow-up period of 1.3 years per patient (standard deviation = 0.29 years). Assessment of the Tayside outpatient clinic log and GP referral letters showed that, of the 215 patients scanned in 1 year, 30 (14%) were referred to neurology clinics because of headache. Of these 30 patients, 12 (40%) were referred before, or at the same time as their CT scan request, and the remaining 18 (60%) were referred after their brain CT. The overall referral rate per 100 patient years was 10.4 (95% CI = 6.3 to 14.5). The diagnoses made by neurologists of the 30 patients referred to clinic are shown in Table 2, and the brain CT findings are shown in Table 3.

Five (2.3%) patients died in the follow-up period: one patient had meningeal deposits of metastatic lung cancer seen on the study brain CT; three other patients died of unrelated conditions including pneumonia (n = 1), pulmonary embolism (n = 1), and acute renal failure (n = 1). No information was available for one of the deceased patients.

DISCUSSION