Cigarette smoking, patient age inversely, and the size and location of the unruptured intracranial aneurysm seem to be risk factors for aneurysm rupture. The risk of bleeding decreases with a very long-term follow-up.

Objective: To determine the nationwide incidence of subarachnoid hemorrhage (SAH) and report nationwide changes in smoking rates between 1998 and 2012 in Finland.Methods: In this register-based study, we utilized the nationwide Causes of Death Register and Hospital Discharge Register in identifying SAH events between 1998 and 2012. Population statistics in Finland, which were obtained through a database of Statistics Finland, were used to calculate crude annual incidence rates of SAH. For the direct age standardization of crude incidence rates, we used the European Standard Population (ESP) 2013. Data on changes in nationwide smoking rates between 1998 and 2012 were extracted from a database of the National Institute for Health and Welfare.Results: For the total of 79,083,579 cumulative person-years, we identified 6,885 people with SAH. Sudden deaths from SAH away from hospitals or in emergency rooms accounted for 1,771 (26%) of the events. Crude nationwide annual incidence rates varied between 6.2 and 10.0 per 100,000 persons, and increased by age particularly in women. Among 70-to 75-year-old women, the incidence of SAH was highest (22.5 per 100,000 persons). The 3-year average of ESP standardized incidence decreased 24% from 11.7 in 1998-2000 to 8.9 per 100,000 persons in 2010-2012. Daily smoking decreased 30% between 1998 and 2012.Conclusions: The incidence of SAH seems to be decreasing. This tendency may be coupled with changes in smoking rates. The incidence of SAH in Finland is similar to other Nordic countries.

following, we try to further conceptualize and clarify the results. First, Kirchoff-Torres and Labovitz are concerned about the reliability of the lifelong unruptured intracranial aneurysm (UIA) rupture risk estimation of 29%, especially if used in predicting the rupture risk in patients with UIAs. We agree that such a rough overall estimate should not be used in individual risk predictions for a future subarachnoid hemorrhage (SAH). If this is the case, our results have been overgeneralized, indeed. The figure 29% has been reported only for epidemiological purposes. As an anecdote, the Finnish adult population has ≈90 000 UIAs (2%-3% prevalence) and ≈600 aneurysmal SAHs annually. This means that the lifelong rupture risk is ≈30% with a constant IA rupture rate, population structure, risk factor status, and life expectancy of 45 years after the age of 30 years.Second, Kirchoff-Torres and Labovitz stated that because the previous SAH is an independent risk factor for a future SAH, external validity in our study is questionable. Their comment relies on a (overgeneralized) misconception about previous natural history studies. 3 SAHs) did not adjust their analyses for risk factors (studies had no 3 or limited 2 data on lifestyle risk factors), and thus it is impossible to know whether a previous SAH was an independent risk factor in these studies. 2,3 If hypertensive patients with a previous SAH and UIAs continue smoking, the risk of another SAH in the future is likely increased. If smoking and hypertension are eliminated, this is unlikely true. Shortly, if a study has no internal validity, it has no external validity.Third, Kirchoff-Torres and Labovitz have doubts about the finding showing that small IAs do rupture. Conceivably, doctors who focus on (short-term) follow ups instead of treatments of IAs can often be left with an impression that small UIAs do not rupture, especially if patients with ruptures are treated elsewhere. The vast majority of the unruptured and ruptured IAs are small, as discussed in our article.1 Thus, the recent epidemiological research has tried to identify other risk factors for rupture than the size. The best available studies on the risk factors, that is, the unselected prospective population-based studies 4,5 and the unselected Finnish lifelong series, 1 are in accordance with each other and strongly question the principle of using solely the size of an UIA in rupture risk estimations. If the size is used as the only criterion, for instance, preventive treatments will have an extremely small effect on the incidence of SAH.In brief, our study suggests that treatment decisions of UIAs should perhaps be based on the risk factor status. However, despite the high internal validity, we agree that individual treatment decisions should not be solely based on any given figure in this epidemiological article. DisclosuresNone.

Of the 118 patients (61 women), 28 (24%) had multiple (≥2) UIAs. The mean and median age at the time of diagnosis of UIAs was 42.8 and 43.5 years (range, 22.6-60.7 years), respectively. Follow-up time Background and Purpose-Our aim was to define for the first time the lifelong natural course of unruptured intracranial aneurysms (UIAs) and identify high-risk and low-risk patients for the rupture. Methods-One hundred and eighteen patients (61 women) with UIAs were diagnosed between 1956 and 1978 and followed up until death or subarachnoid hemorrhage (SAH). The median age at the diagnosis was 43.5 years (range, 22.6-60.7 years). The median size of the UIA at the diagnosis was 4 mm (range, 2-25 mm). Analyzed risk factors for a rupture included sex, age, cigarette smoking, systolic blood pressure values, diagnosed hypertension, UIA size, and number of UIAs. Results-Thirty four (29%) out of 118 people had SAH during the lifelong follow-up. The median age at SAH was 51.3 years (range, 30.1-71.8 years). The annual rupture rate per patient was 1.6%. Female sex, current smoking, and aneurysm size of ≥7 mm in diameter were risk factors for a lifetime SAH. Depending on the risk factor burden, the lifetime risk of an aneurysmal SAH varied from 0% to 100%, and the annual rupture rate from 0% to 6.5%. Of the 96 patients with small (<7 mm) UIAs, 24 (25%) had an aneurysmal SAH during the follow-up. Conclusions-Almost Data GatheringThe data gathering protocol has been described previously. [5][6][7][8] In brief, the data on risk factors were collected using telephone interviews (patients and relatives), written questionnaires, and medical records obtained from the study hospital, other hospitals, and healthcare centers. Those who were alive between 1996 and 1998 were also interviewed in the outpatient clinic. At the same time, a follow-up computed tomography angiogram was performed. 7,14 For all patients who died, autopsy reports and death certificates were scrutinized. The approval for the surveys and follow-up data collection had been obtained in 1995 and 2009 from Helsinki University Central Hospital and Turku University Hospital ethics committees. Studied Risk Factors Systolic Blood PressureSBP values available in medical data in hospitals and healthcare centers were recorded at the follow-ups. The mean SBP value of all measurements (mean 3 measurements per person, range, 0-15) within the last 5 years before death or SAH was used in statistical analyses. If only one SBP value (24 patients) was recorded within the last 5 years, this was used as a cross-sectional data in statistical analyses. When only 5 years older SBP values were available, the most recent SBP was used in statistical analyses. Smoking StatusSmoking status was recorded as a never-smoker if the patient had no regular smoking history and did not report smoking at any of the follow-ups. If the patient quitted smoking 12 months before the death or SAH, he/she was considered as an ex-smoker. In other occasions, patients were considered to be current smokers. Aneu...

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