JNEPHROL 2013; 26 ( 5 ) : 919-924

original article

DOI: 10.5301/jn.5000250

Screening for transient ischemic attacks in hemodialysis patients Albert Power 1, Claire Edwards 1, Jan Sawyer 1, Damir Tandaric 1, Dima Dahdaleh 2, David Taube 1, Neill Duncan 1

Abstract

Imperial College Renal & Transplant Center, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London - UK 2 National Hospital for Neurology and Neurosurgery, London - UK 1

implications for the detection and treatment of TIA in dialysis.

Background: Rapid recognition and management of transient ischemic attacks (TIAs) reduce incident strokes in the general population, but similar data are lacking in dialysis patients, who form a high-risk group for this pathology. We systematically screened hemodialysis patients for TIA to estimate its incidence and determine whether there was significant scope to reduce subsequent strokes by risk modification. Methods: Patients established on hemodialysis at a satellite dialysis unit at our center were screened prospectively using weekly symptom questionnaires over a 12-month period. Following clinical review, patients who screened positive were urgently referred to a TIA clinic, and all stroke and TIA and stroke events were recorded. Results: A total of 304 patients were screened over 2,594 total patient months of follow-up (1st November 2009 to 1st November 2010). Six strokes occurred, of which 5 were ischemic (a rate of 23.1/1,000 patientyears). No patients screened positive for a TIA, despite predicted rates of 4.2/1,000 patient-years (95% confidence interval, 1.4-9.7/1,000 patient-years). One ischemic stroke was preceded by symptoms compatible with a TIA, although this was ascertained in retrospect and not during screening. Conclusions: Based on the first study of its kind to date, systematic screening for TIA has a low yield and cannot be relied on alone to identify patients at higher risk of cerebrovascular events. The confounding presence of symptoms attributable to uremia, neuropathy, hypotension and dysglycemia could reduce the sensitivity of established tests, with significant

Key words: Cerebrovascular, Hemodialysis, Stroke, Transient ischemic attack

Introduction Transient ischemic attack (TIA) is a clinical diagnosis defined by a rapidly developing loss of focal cerebral function lasting 0.9), there was considerable variability in reporting paresthesiae, visual disturbance and headache. This fluctuation in consistency within symptom category casts doubt on the ability of these questions to

© 2013 Società Italiana di Nefrologia - ISSN 1121-8428

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Power et al: TIA screening in HD patients

TABLE II INTRA-CLASS COEFFICIENTS FOR TIA SYMPTOM REPORTING Symptom

Intra-class coefficient

95% Confidence interval

Pins and needles

0.93

0.85-0.97

Facial/limb numbness

0.90

0.76-0.96

Arm weakness

0.99

0.98-0.99

Leg weakness

0.96

0.89-0.94

Facial weakness

0.95

0.91-0.98

Visual disturbance

0.95

0.28-0.98

Headache

0.92

0.59-0.97

Problem with speech

0.94

0.86-0.97

Confusion

0.99

0.99-1.00

TIA = transient ischemic attack.

detect true positive and negative responses and could relate to changes in dialysis schedules, patients’ psychological status, blood pressure or fatigue in reporting resultant from repeated questioning.

Discussion Systematic screening for symptoms of TIA in HD patients did not result in a positive diagnosis over a 12-month study period and did not identify those patients who subsequently had a stroke. The reasons for this require further evaluation in light of the ongoing National Stroke Strategy in the United Kingdom. The true incidence of TIA in HD patients remains unquantified. In the 2011 United States Renal Data System (USRDS) report, stroke and TIA were combined as a single measure. The classic 4:1 ratio between stroke and TIA in the general population has yet to be validated in HD. It is possible that the pathophysiology of ischemic stroke in HD is distinct from that of the general population and that TIA does not presage stroke in these patients. In a parallel analysis of estimated glomerular filtration rate (eGFR) in patients attending a specialist TIA clinic at our center (July 2010 through January 2011, unpublished data), 39/241 of referrals (16%) occurred in those with an eGFR