Age and sex-specific incidence rates of group A streptococcal pharyngitis between 2010 and 2018: a population-based study

Aim: Group A streptococcus (GAS) pharyngitis is a common clinical infection with significant morbidity but remains understudied. Materials & methods: We sought to assess the rates of testing and incidence of GAS pharyngitis in Calgary, Alberta based on age and sex. Results: A total of 1,074,154 tests were analyzed (58.8% female, mean age 24.8 years) of which 16.6% were positive. Age-standardized testing and positivity was greatest in the 5–14 years age group and lowest in persons over 75 years. Females had greater rates of testing and positivity throughout. Testing rates (incidence rate ratios: 1.40, 95% CI: 1.39–1.41) and case rates (incidence rate ratios: 1.36, 95% CI: 1.33–1.39) increased over time. Conclusion: Future studies should focus on evaluating disparities in testing and treatment outcomes to optimize the approach to this infection.

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A Population-Based Study of Incidence of Myeloproliferative Neoplasms in Sweden Between 2000 and 2012

Blood ◽

10.1182/blood.v126.23.1605.1605 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1605-1605

Author(s):

Malin Hultcrantz ◽

Therese M-L Andersson ◽

Ola Landgren ◽

Paul W Dickman ◽

Bjorn Andreasson ◽

...

Keyword(s):

Incidence Rate ◽

Confidence Intervals ◽

Research Funding ◽

Myeloproliferative Neoplasms ◽

Population Based ◽

Incidence Rates ◽

Annual Incidence Rate ◽

Swedish Population ◽

Population Based Study ◽

Cancer Register

Abstract Background The Myeloproliferative neoplasms (MPNs) consists of the subtypes polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF), and MPN unclassifiable (MPN-U). The incidence rates of these diseases vary substantially between different reports, ranging from 1.15 to 4.99/100,000 person-years. However, in a recent metaanalysis, there was no significant difference in MPN incidence between Europe and North America and the variations in incidence may therefore reflect the quality of the cancer registers and reporting of MPNs. In addition, there is a limited number of reports on MPN incidence during more recent years. Therefore, we assessed the incidence of MPN based on the Swedish Cancer Register, a high-quality population-based cancer register between 2000 and 2012. Patients and Methods The Swedish Cancer Register was used to identify all patients diagnosed with an MPN between January 1st 2000 and December 31st 2012. These Swedish Cancer Registers have very high levels of quality and completeness. Between 2008 and 2012, the reporting of newly diagnosed MPN to the cancer register was >92%. Information on the Swedish population was obtained from the Human Mortality Database (www.mortality.org). Based on information from these registers, incidence rates of MPNs with 95% confidence intervals (CIs) were calculated. Confidence intervals were estimated on the log scale. In addition, the incidence rate in relation to MPN subtype, age group (18-39, 40-49, 50-59, 60-69, 70-79, and ³80 years), as well as calendar year of diagnosis was assessed. Results A total of 5,442 MPN patients were reported to the cancer register between 2000 and 2012. During these years, there were 1,810 incident cases of PV, 1,862 of ET, 636 of PMF, and 1,134 with MPN-U. Between January 1st 2000 and December 31st 2012, the population in Sweden increased from 8,861,426 to 9,555,893 inhabitants. The overall annual incidence rate of MPN was 5.83 (95% CI 5.68-5.99)/100,000 persons. The incidence rate of PV was 1.94 (1.85-2.03), ET 2.00 (1.91-2.09), PMF 0.68 (0.63-0.74), and MPN-U 1.22 (1.15-1.29) per 100,000 person-years. In addition, there was a strong correlation between age and incidence of MPN with incidence rates being substantially higher among the older age groups (Table). The overall incidence rate of MPNs increased during the study period, from 5.06 (4.55-5.62)/100,000 person-years in the year 2000 to 5.98 (5.45-6.55)/100,000 person-years in 2012. The incidence rate of PV was similar throughout the study period, the incidence was 2.05 (1.74-2.42)/100,000 person-years in 2000 and 2.12 (1.81-2.47)/100,000 person-years in 2012. The annual incidence rate of ET and PMF increased, from 1.62 (1.34-1.95) to 2.49 (2.15-2.87) per 100,000 persons for ET and from 0.36 (0.24-0.53) to 0.86 (0.67-1.10) per 100,000 persons for PMF between 2000 and 2012. Conversely, the incidence of MPN-U decreased, 1.03 (0.81-1.29) to 0.52 (0.38-0.71)/100,000 person-years between 2000 and 2012. Summary and Conclusions In this large population-based study, the incidence of MPN was higher than previously reported in both European and North American studies. As earlier lower incidence rates likely are an effect of limited coverage of cancer registers, there may be an underreporting of MPNs in many European and American countries. The increase in MPN incidence rates during the study period may reflect increasing life expectancy of the Swedish population, improved reporting to the cancer register as well as changes in the classification and diagnostic systems. Similarly, the decrease in incidence of MPN-U is also likely a result of improved diagnostics during more recent years. In conclusion, the MPN incidences rates reported here are presumably more accurate compared to earlier reports due to the high level of coverage and accuracy of the Swedish registers. Table 1. Incidence rates of MPNs overall and in relation to subtype and age at diagnosis Total number MPN diagnosed 2000-2012 Incidence/100 000 person-years (95% confidence interval) All MPN 5,442 5.83 (5.68-5.99) Subtype PV 1,810 1.94 (1.85-2.03) ET 1,862 2.00 (1.91-2.09) PMF 636 0.68 (0.63-0.74) MPN-U 1,134 1.22 (1.15-1.29) Age at diagnosis (years) 18-39 226 0.67 (0.59-0.76) 40-49 361 2.26 (2.04-2.51) 50-59 769 4.92 (4.58-5.28) 60-69 1,228 9.54 (9.02-10.1) 70-79 1,680 18.99 (18.1-19.9) >80 1,178 18.92 (17.87-20.03) Disclosures Landgren: BMJ Publishing: Honoraria; Bristol-Myers Squibb: Honoraria; Medscape: Honoraria; Onyx: Honoraria; Celgene: Honoraria; International Myeloma Foundation: Research Funding; Medscape: Consultancy; BMJ Publishing: Consultancy; Onyx: Research Funding; Bristol-Myers Squibb: Consultancy; Onyx: Consultancy; Celgene: Consultancy.

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Trends in Incidence and Histological Pattern of Thyroid Cancer in Ho Chi Minh City, Vietnam (1996-2015): A Population-Based Study

10.21203/rs.3.rs-125916/v1 ◽

2021 ◽

Author(s):

Dung Pham ◽

Hien Nguyen ◽

An Phung ◽

Tung Bui ◽

Thach Tran ◽

...

Keyword(s):

Thyroid Cancer ◽

Incidence Rate ◽

Papillary Thyroid Cancer ◽

Population Based ◽

Incidence Rates ◽

Ho Chi Minh City ◽

Similar Distribution ◽

Papillary Thyroid ◽

Population Based Study ◽

Histological Pattern

Abstract BackgroundThe burden and trend of thyroid cancer in Vietnam have not been well documented. This study aimed to investigate the trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City from 1996 to 2015.MethodsA population-based study retrieved data from the Ho Chi Minh City Cancer Registry during 1996-2015. Trends in the incidence of thyroid cancer were investigated based on age, gender, and histology for each 5-year period. Annual percentage change (APC) in incidence rates was estimated using Joinpoint regression analysis.ResultsIn the study period, there were 5 953 thyroid cancer cases (men-to-women ratio 1:4.5) newly diagnosed in Ho Chi Minh City with the mean age of 42.9 years (±14.9 years). The age-standardized incidence rate of thyroid cancer increased from 2.4 per 100 000 during 1996-2000 (95% confidence interval [95% CI]: 2.2-2.6) to 7.5 per 100 000 during 2011-2015 (95% CI: 7.3-7.9), corresponded to an overall APC of 8.7 (95% CI 7.6-9.9). The APC in men and women was 6.2 (95% CI: 4.2-8.2) and 9.2 (95% CI: 8.0-10.4), respectively. The incidence rate in the <45 years age group was the highest diagnosed overall and increased significantly in both men (APC 11.0) and women (APC 10.1). Both genders shared similar distribution of subtype incidences, with papillary thyroid cancer constituted the most diagnosed (73.3% in men and 85.2% in women). The papillary thyroid cancer observed a markedly increase overall (APC of 10.7 (95% CI 9.3-12.0)).ConclusionsThere were appreciable increases in the age-standardized incidence rate of thyroid cancer in both genders, mainly contributed by the papillary subtype. The age of patients at diagnosis decreased gradually. The widespread utilization of advanced diagnostic techniques and healthcare accessibility improvement might play a potential role in these trends. Further investigations are needed to comprehend the risk factors and trends fully.

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Trends in occurrence and 30-day mortality of infective endocarditis in adults: population-based registry study in Finland

BMJ Open ◽

10.1136/bmjopen-2018-026811 ◽

2019 ◽

Vol 9 (4) ◽

pp. e026811 ◽

Cited By ~ 9

Author(s):

Elina Ahtela ◽

Jarmo Oksi ◽

Pekka Porela ◽

Tommi Ekström ◽

Paivi Rautava ◽

...

Keyword(s):

Sex Differences ◽

Infective Endocarditis ◽

Incidence Rate ◽

Hospital Admissions ◽

Temporal Trends ◽

Population Based ◽

Mortality Data ◽

Annual Increase ◽

Rate Ratios ◽

Age And Sex

ObjectivesInfective endocarditis (IE) is a life-threatening disease associated with significant mortality. We studied recent temporal trends and age and sex differences in the occurrence and short-term mortality of IE.DesignPopulation based retrospective cohort study.SettingData of IE hospital admissions in patients aged ≥18 years in Finland during 2005–2014 and 30-day all-cause mortality data were retrospectively collected from mandatory nationwide registries from 38 hospitals.OutcomesTrends and age and sex differences in occurrence. Thirty-day mortality.ResultsThere were 2611 cases of IE during the study period (68.2% men, mean age 60 years). Female patients were significantly older than males (62.0 vs 59.0 years, p=0.0004). Total standardised annual incidence rate of IE admission was 6.33/100 000 person-years. Men had significantly higher risk of IE compared with women (9.5 vs 3.7/100 000; incidence rate ratios [IRR] 2.49; p<0.0001) and difference was most prominent at age 40–59 years (IRR 4.49; p<0.0001). Incidence rate varied from 5.7/100 000 in 2005 to 7.1/100 000 in 2012 with estimated average 2.1% increase per year (p=0.036) and similar trends in both sexes. Significant increasing trend was observed in patients aged 18–29 years and 30–39 years (estimated annual increase 7.6% and 7.2%, p=0.002) and borderline in patients aged 40–49 years (annual increase 3.8%, p=0.08). In older population, IE incidence rate remained stable. The overall 30-day mortality after IE admission was 11.3%. Mortality was similar between sexes, increased with ageing, and remained similar during the study period.ConclusionsOccurrence of IE is increasing in young adults in Finland. Men, especially middle-aged, are at higher risk for IE compared with women. Thirty-day mortality has remained stable at 11%, increased with ageing, and was similar between sexes.

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Time Trends in Epidemiology and Characteristics of Psoriatic Arthritis Over 3 Decades: A Population-based Study

The Journal of Rheumatology ◽

10.3899/jrheum.080691 ◽

2009 ◽

Vol 36 (2) ◽

pp. 361-367 ◽

Cited By ~ 94

Author(s):

FLORANNE C. WILSON ◽

MURAT ICEN ◽

CYNTHIA S. CROWSON ◽

MARIAN T. McEVOY ◽

SHERINE E. GABRIEL ◽

...

Keyword(s):

Psoriatic Arthritis ◽

Time Trends ◽

Population Based ◽

Incidence Rates ◽

Population Based Study ◽

Physician Awareness ◽

Adjusted Incidence ◽

Diagnosis Date ◽

Age And Sex

Objective.To determine time trends in incidence, prevalence, and clinical characteristics of psoriatic arthritis (PsA) over a 30-year period.Methods.We identified a population-based incidence cohort of subjects aged 18 years or over who fulfilled ClASsification of Psoriatic ARthritis (CASPAR) criteria for PsA between January 1, 1970, and December 31, 1999, in Olmsted County, Minnesota, USA. PsA incidence date was defined as the diagnosis date of those who fulfilled CASPAR criteria. Age- and sex-specific incidence rates were estimated and age- and sex-adjusted to the 2000 US White population.Results.The PsA incidence cohort comprised 147 adult subjects with a mean age of 42.7 years, and 61% were men. The overall age- and sex-adjusted annual incidence of PsA per 100,000 was 7.2 [95% confidence interval (CI) 6.0, 8.4] with a higher incidence in men (9.1, 95% CI 7.1, 11.0) than women (5.4, 95% CI 4.0, 6.9). The age- and sex-adjusted incidence of PsA per 100,000 increased from 3.6 (95% CI 2.0, 5.2) between 1970 and 1979 to 9.8 (95% CI 7.7, 11.9) between 1990 and 2000 (p for trend < 0.001). The point prevalence per 100,000 was 158 (95% CI 132, 185) in 2000, with a higher prevalence in men (193, 95% CI 150, 237) than women (127, 95% CI 94, 160). At incidence, most PsA subjects had oligoarticular involvement (49%) with enthesopathy (29%).Conclusion.The incidence of PsA has been rising over 30 years in men and women. Reasons for the increase are unknown, but may be related to a true change in incidence or greater physician awareness of the diagnosis.

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Trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City, Vietnam (1996–2015): a population-based study

BMC Cancer ◽

10.1186/s12885-021-08023-z ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Dung X. Pham ◽

Hien D. Nguyen ◽

An H. T. Phung ◽

Tung D. Bui ◽

Thach S. Tran ◽

...

Keyword(s):

Thyroid Cancer ◽

Incidence Rate ◽

Papillary Thyroid Cancer ◽

Population Based ◽

Incidence Rates ◽

Ho Chi Minh City ◽

Similar Distribution ◽

Papillary Thyroid ◽

Population Based Study ◽

Histological Pattern

Abstract Background The burden and trend of thyroid cancer in Vietnam have not been well documented. This study aimed to investigate the trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City from 1996 to 2015. Methods A population-based study retrieved data from the Ho Chi Minh City Cancer Registry during 1996–2015. Trends in the incidence of thyroid cancer were investigated based on age, gender, and histology for each 5-year period. Annual percentage change (APC) in incidence rates was estimated using Joinpoint regression analysis. Results In the study period, there were 5953 thyroid cancer cases (men-to-women ratio 1:4.5) newly diagnosed in Ho Chi Minh City with the mean age of 42.9 years (±14.9 years). The age-standardized incidence rate of thyroid cancer increased from 2.4 per 100,000 during 1996–2000 (95% confidence interval [95% CI]: 2.2–2.6) to 7.5 per 100,000 during 2011–2015 (95% CI: 7.3–7.9), corresponded to an overall APC of 8.7 (95% CI 7.6–9.9). The APC in men and women was 6.2 (95% CI: 4.2–8.2) and 9.2 (95% CI: 8.0–10.4), respectively. The incidence rate in the < 45 years age group was the highest diagnosed overall and increased significantly in both men (APC 11.0) and women (APC 10.1). Both genders shared similar distribution of subtype incidences, with papillary thyroid cancer constituted the most diagnosed (73.3% in men and 85.2% in women). The papillary thyroid cancer observed a markedly increase overall (APC of 10.7 (95% CI 9.3–12.0)). Conclusions There were appreciable increases in the age-standardized incidence rate of thyroid cancer in both genders, mainly contributed by the papillary subtype. The age of patients at diagnosis decreased gradually. The widespread utilization of advanced diagnostic techniques and healthcare accessibility improvement might play a potential role in these trends. Further investigations are needed to comprehend the risk factors and trends fully.

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224. Evaluating the Epidemiology of Bloodstream Infections: A Population-Based Study

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab466.426 ◽

2021 ◽

Vol 8 (Supplement_1) ◽

pp. S219-S220

Author(s):

Elaha Niazi ◽

Kwadwo Mponponsuo ◽

Ranjani Somayaji ◽

Elissa Rennert-May ◽

John Conly ◽

...

Keyword(s):

Large Population ◽

Age Groups ◽

Bloodstream Infections ◽

Population Based ◽

Incidence Rates ◽

Population Based Study ◽

Health Region ◽

Canadian Health ◽

Over Time ◽

Age And Sex

Abstract Background Bloodstream infections (BSI) are a major cause of morbidity, mortality, and health care costs worldwide. Population-based studies are key to assess BSI epidemiology over time while minimizing selection bias but remain limited. Therefore, we aimed to assess the incidence of BSI in a large Canadian health region in a contemporary period. We hypothesized that there would be significant age and sex-based differences including over time. Methods We conducted a retrospective cohort study from 2011 through 2018 using a population-based microbiology database to determine the annual age- and sex-specific BSI testing and case rates with the census as the population reference. BSI was defined as a positive blood culture for a pathogen. Episodes > 30 days apart were included for analysis. Incidence rate ratios (IRR) for testing and case rates including by sex were calculated to assess changes over time. All analyses were run at a two-sided α of 0.05 and were conducted with R 4.0.4. Results A total of 154,147 distinct individuals (49.9% male) were analyzed and 22,869 (14.8%) had a BSI at the first encounter in the study period. Overall BSI testing incidence ranged from 1529 to 1707 per 100,000 person-years and case incidence ranged from 180 to 292 per 100,000 person-years. Testing and case incidence for BSI was greatest in the 0-4 and 75+ years age groups (p < 0.01). Males compared to females had greater testing and case incidence rates in young and old age groups, but females had greater rates in the 15-44 years groups (p < 0.01). Overall IRR for cases comparing 2018 to 2011 was 0.62 (95% CI 0.59-0.65) reflecting a significant decrease over time. Testing also decreased over the study period with an IRR of 0.90 (95% CI 0.88-0.91). Testing and case IRRs were not significantly different stratified by sex. Incidence rates (per 100,000 person-years) of BSI testing and cases by sex from 2011 through 2018 in a Canadian health region Conclusion In our large population-based study of BSI, we identified that BSI remain frequent and the youngest and oldest age groups as well as males in these age groups have the greatest BSI incidence rates which may reflect both biological sex and gender-based differences. Encouragingly, BSI incidence rates have decreased over time at a greater increment relative to testing rates. Future studies of BSI should focus on pathogen and outcome-based evaluations. Disclosures All Authors: No reported disclosures

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Epidemiology of subtypes of hypothyroidism in Denmark

Acta Endocrinologica ◽

10.1530/eje.1.02068 ◽

2006 ◽

Vol 154 (1) ◽

pp. 21-28 ◽

Cited By ~ 115

Author(s):

Allan Carlé ◽

Peter Laurberg ◽

Inge Bülow Pedersen ◽

Nils Knudsen ◽

Hans Perrild ◽

...

Keyword(s):

Incidence Rate ◽

Iodine Deficiency ◽

Post Partum ◽

Population Based ◽

Iodine Intake ◽

Incidence Rates ◽

Overt Hypothyroidism ◽

Limited Information ◽

Danish Population ◽

Population Based Study

Objective: Studies of hypothyroidism are often based on referred patients, and limited information is available on the incidence rates of subtypes of hypothyroidism in the general population. We therefore studied incidences of subtypes of primary, overt hypothyroidism in a Danish population cohort and compared incidences in two subcohorts with different levels of iodine intake. Design: A prospective population-based study, monitoring a well-defined cohort representative of the Danish population. Methods: The Danish Investigation of Iodine Intake and Thyroid Diseases registry of hyper- and hypothyroidism was established as part of the monitoring of the iodine fortification of salt in Denmark. A computer-based system linked to laboratory databases identified all patients diagnosed with new, biochemically overt hypothyroidism in populations living in Aalborg (moderate iodine deficiency, n = 311 102) and Copenhagen (mild iodine deficiency, n = 227 632). We subsequently evaluated all identified patients to verify incident thyroid disease, and subclassified hypothyroidism into nosological types. Results: During a 4-year period (2 027 208 person-years) 685 new cases of overt hypothyroidism were diagnosed in the cohort; the incidence rate was 32.8 per 100 000 person-years (standardised to the Danish population). Nosological types of hypothyroidism were: spontaneous (presumably autoimmune) 84.4%, post-partum 4.7%, amiodarone-associated 4.0%, subacute thyroiditis 1.8%, previous radiation or surgery 1.8%, congenital 1.6% and lithium-associated 1.6%. Crude incidence rates were 29.0 around Aalborg and 40.6 in an area of Copenhagen. The higher incidence rate of hypothyroidism in the area with higher iodine intake was caused solely by more cases of spontaneous (presumably autoimmune) hypothyroidism, whereas the incidence of non-spontaneous hypothyroidism (all types combined) was significantly lower in the area with higher iodine intake. Conclusion: In a population-based study we observed a higher incidence of hypothyroidism with higher iodine intake. This was due solely to the entity of spontaneous hypothyroidism. The occurrence of overt hypothyroidism was relatively low in Denmark.

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Is insomnia a risk factor for new-onset asthma? A population-based study in Taiwan

BMJ Open ◽

10.1136/bmjopen-2017-018714 ◽

2017 ◽

Vol 7 (11) ◽

pp. e018714 ◽

Cited By ~ 4

Author(s):

Yu-Chieh Lin ◽

Chih-Cheng Lai ◽

Chih-Chiang Chien ◽

Chin-Ming Chen ◽

Shyh-Ren Chiang ◽

...

Keyword(s):

Risk Factor ◽

Incidence Rate ◽

Large Population ◽

Population Based ◽

Control Group ◽

Population Based Study ◽

The Difference ◽

Rate Ratios ◽

New Onset

ObjectivesTo determine whether insomnia at baseline is a risk factor for new-onset asthma.MethodsWe recruited 48 871 patients with insomnia (insomnia group) newly diagnosed between 2002 and 2007, and 97 742 matched controls without insomnia (control group) from Taiwan’s Longitudinal Health Insurance Database 2000. All of the patients were followed up for 4 years to see whether new-onset asthma developed. Patients with previous asthma or insomnia were excluded. The Poisson regression was used to estimate the incidence rate ratios (IRRs) and 95% CIs of asthma. Cox proportional hazard regression was used to calculate the risk of asthma between the two groups.ResultsAfter a 4-year follow-up, 424 patients in the insomnia group and 409 in the control group developed asthma. The incidence rate of asthma was significantly higher in the insomnia group (22.01vs10.57 per 10 000 person-years). Patients with insomnia have a higher risk of developing new-onset asthma during the 4-year follow-up (HR: 2.08, 95% CI 1.82 to 2.39). The difference remained significant after adjustment (adjusted HR: 1.89, 95% CI 1.64 to 2.17).ConclusionsThis large population-based study suggests that insomnia at baseline is a risk factor for developing asthma.

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Incidence and prevalence of intracranial aneurysms and hemorrhage in Olmsted County, Minnesota, 1965 to 1995

Neurology ◽

10.1212/wnl.51.2.405 ◽

1998 ◽

Vol 51 (2) ◽

pp. 405-411 ◽

Cited By ~ 95

Author(s):

V. V. Menghini ◽

R. D. Brown ◽

J. D. Sicks ◽

W. M. O'Fallon ◽

D. O. Wiebers

Keyword(s):

Incidence Rate ◽

Medical Records ◽

Population Based ◽

Incidence Rates ◽

Olmsted County ◽

Anterior Circulation ◽

Unique Data ◽

Adjusted Incidence Rate ◽

Adjusted Incidence ◽

Age And Sex

Background: There are no previous reports of the incidence rate of intracranial saccular aneurysms in a defined population.Methods: Medical records of all residents of Olmsted County, MN, with a possible intracranial saccular aneurysm (IA) were reviewed. Incidence rates and prevalence of symptomatic and asymptomatic IAs, aneurysmal intracranial hemorrhage (ICH), and frequency of IA detection based on size and site were determined.Results: A total of 348 IAs were detected among 270 persons during the 31-year period from 1965 to 1995, including 188 symptomatic patients at presentation(166 with ICH). The age- and sex-adjusted incidence rate for IAs excluding asymptomatic autopsy cases was 9.0/100,000 person-years (P-Y; 95% CI, 7.8 to 10.2). The rate of detection in women (10.7/100,000 P-Y; 95% CI, 8.9 to 12.4) was higher than in men. The highest incidence of IA was among those age 55 to 64 years in men, and 65 to 74 years in women. The incidence rate of aneurysmal ICH was 6.9/100,000 P-Y (95% CI, 5.9 to 8.0). Aneurysms were seven times more likely to be detected in the anterior circulation, and this ratio was not altered significantly by age or gender. On January 1, 1990, the age- and sex-adjusted prevalence rate of identified IAs was 83.4/100,000 population (95% CI, 64.1 to 102.7).Conclusions: This study provides unique data on the population-based incidence and prevalence rates of IAs.

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