Measuring the Prevalence of Stroke

Abstract

pairment. Although this combination of questions was chosen as having the optimal sensitivity and specificity in a validation cohort of 384 elderly Germans [3] , and responses were screened by neurologists, the accuracy of the adapted questionnaire is difficult to judge. The original Stroke Symptom Questionnaire also included questions about limb weakness, facial weakness and sensory disturbance and included photographs to illustrate facial weakness and the visual disturbance most commonly associated with stroke. The slimmed-down version used by Jungehulsing et al. [1] would very probably have somewhat reduced sensitivity. Moreover, given the fact that many strokes are relatively mild and recover within a few days or weeks, a significant proportion of elderly individuals are likely to have forgotten about stroke symptoms, and even physician-diagnosed strokes, that occurred many years previously. However, the consequent underestimation of stroke prevalence is likely to be compensated, or possibly reversed, by overdiagnosis of strokelike symptoms that had in fact been due to some other cause. Overall, therefore, the estimate of prevalence was probably reasonably accurate in the 37.5% of the households that responded. Moreover, any concern about possible overdiagnosis due to incorrect interpretation of the very limited clinical data available should be tempered by the fact that minor stroke-like symptoms appear to be informative irrespective of the correct diagnosis. In the REGARDS study, individuals without a previous physiStroke is common and causes considerable morbidity and mortality. Given the strong association between stroke incidence and increasing age, the ageing of the population means that the prevalence of stroke could well be rising and so accurate and up-to-date measurement is important for the planning and delivery of effective health (and social) care provision. The community survey reported by Jungehulsing et al. [1] is therefore timely and important. In a postal survey of 75,720 households containing at least one person over 50 years old in Berlin, with a response rate of 37.5%, they estimated the prevalence of a physician-diagnosed stroke to be 4.5% and the rate of prior stroke symptoms to be 2.7–5.0% (depending on the symptom). Combining the rates of reported stroke history with previous stroke symptoms, the prevalence of stroke was estimated to be 7.6%, which is within the range reported in previous studies from other countries [2] . Higher stroke prevalence was associated with increasing age, male sex, non-German nationality, living alone, lower educational achievement and a positive family history of stroke. The attempt to identify stroke events that had not been reported to, or diagnosed by, a doctor was an important aspect of the study. Subjects were questioned about previous stroke symptoms using an adapted version of the Stroke Symptom Questionnaire, with identification of previously undiagnosed stroke based on a positive response to questions about speech difficulty or visual imReceived: February 17, 2008 Accepted: February 18, 2008 Published online: April 18, 2008