Chronic hyponatremia and association with osteoporosis among a large racially/ethnically diverse population.

Chronic hyponatremia may contribute to decreased bone density. We studied 341,003 men and women who underwent DXA testing and observed that individuals with chronic hyponatremia (sodium < 135 mEq/L) had an 11% greater likelihood of having osteoporosis. There was a dose-dependent effect with lower sodium and stronger association with osteoporosis. INTRODUCTION: Chronic hyponatremia has been associated with both neurologic deficits and increased risk of gait abnormalities leading to falls and resultant bone fractures. Whether chronic hyponatremia contributes to decreased bone density is uncertain. We evaluated whether chronic, mild hyponatremia based on serial sodium measurements was associated with increased risk of osteoporosis within a large, ethnically diverse population. METHODS: This is a retrospective cohort study between January 1, 1998 and December 31, 2014 within Kaiser Permanente Southern California, an integrated healthcare delivery system. Men and women were aged ≥ 55 years with ≥ 2 serum sodium measurements prior to dual-energy X-ray absorptiometry (DXA) testing. Time-weighted (TW) mean sodium values were calculated by using the proportion of time (weight) elapsed between sodium measurements and defined as < 135 mEq/L. Osteoporosis defined as any T-score value ≤ - 2.5 of lumbar spine, femoral neck, or hip. RESULTS: Among 341,003 individuals with 3,330,903 sodium measurements, 11,539 (3.4%) had chronic hyponatremia and 151,505 (44.4%) had osteoporosis. Chronic hyponatremic individuals had an osteoporosis RR (95% CI) of 1.11 (1.09, 1.13) compared to those with normonatremia. A TW mean sodium increase of 3 mEq/L was associated with a lower risk of osteoporosis [adjusted RR (95% CI) 0.95 (0.93, 0.96)]. A similar association was observed when the arithmetic mean sodium value was used for comparison. CONCLUSIONS: We observed a modest increase in risk for osteoporosis in people with chronic hyponatremia. There was also a graded association between higher TW mean sodium values and lower risk of osteoporosis. Our findings underscore the premise that chronic hyponatremia may lead to adverse physiological effects and responses which deserves better understanding.

Using winter 2009-2010 to assess the accuracy of methods which estimate influenza-related morbidity and mortality.

We used the winter of 2009-2010, which had minimal influenza circulation due to the earlier 2009 influenza A(H1N1) pandemic, to test the accuracy of ecological trend methods used to estimate influenza-related deaths and hospitalizations. We aggregated weekly counts of person-time, all-cause deaths, and hospitalizations for pneumonia/influenza and respiratory/circulatory conditions from seven healthcare systems. We predicted the incidence of the outcomes during the winter of 2009-2010 using three different methods: a cyclic (Serfling) regression model, a cyclic regression model with viral circulation data (virological regression), and an autoregressive, integrated moving average model with viral circulation data (ARIMAX). We compared predicted non-influenza incidence with actual winter incidence. All three models generally displayed high accuracy, with prediction errors for death ranging from -5% to -2%. For hospitalizations, errors ranged from -10% to -2% for pneumonia/influenza and from -3% to 0% for respiratory/circulatory. The Serfling and virological models consistently outperformed the ARIMAX model. The three methods tested could predict incidence of non-influenza deaths and hospitalizations during a winter with negligible influenza circulation. However, meaningful mis-estimation of the burden of influenza can still result with outcomes for which the contribution of influenza is low, such as all-cause mortality.

Association between maternal inflammatory bowel disease and adverse perinatal outcomes.

OBJECTIVE: To examine whether inflammatory bowel disease (IBD) is associated with ischemic/inflammatory conditions during pregnancy. STUDY DESIGN: A retrospective cohort study using the 2000 to 2012 Kaiser Permanente Southern California maternally-linked medical records (n=395 781). The two major subtypes of IBD, ulcerative colitis and Crohn's diseases were studied. Adjusted odds ratios (ORs) were used to quantify the associations. RESULT: A pregnancy complicated by IBD was associated with increased incidence of small-for-gestational age birth (OR=1.46, 95% confidence interval (CI)=1.14 to 1.88), spontaneous preterm birth (OR=1.32, 95% CI=1.00 to 1.76) and preterm premature rupture of membranes (OR=1.95, 95% CI=1.26 to 3.02). Further stratifying by IBD subtypes, only ulcerative colitis was significantly associated with increased incidence of ischemic placental disease, spontaneous preterm birth and preterm premature rupture of membranes. CONCLUSION: The findings underscore the potential impact of maternal IBD on adverse perinatal outcomes. Clinicians should be aware that the association between IBD and adverse perinatal outcome varies by IBD subtypes.

Ten-year hip fracture incidence rate trends in a large California population, 1997-2006.

UNLABELLED: Hip fractures are a large public health problem with significant negative impact on an individual's overall health and survival. But while the total numbers of persons affected by hip fractures may be anticipated to increase, incidence rates appear to be declining. INTRODUCTION: To describe annual hip fracture incidence rate trends in an integrated health-care organization over 1997-2006, during which a proactive bone health program was initiated program-wide and other secular trends occurred in the population. METHODS: For this ecologic trend study, we identified all men and women ≥45 years old as of January 1 of each year. Incident fractures for each year were identified using ICD-9 diagnosis codes 820-820.9, excluding all subjects who had fractures in prior years. Annual person-time at risk for hip fracture was determined from enrollment data. Sex- and age-specific and adjusted annual incidence rates were calculated. RESULTS: The overall annual hip fracture incidence rate for men declined from 1.52/1,000 person-years in 1997 to 1.29/1,000 person-years in 2006, a 15.3% (95% confidence interval [CI]=6.2-24.5) decrease. For women, incidence declined from 2.65/1,000 person-years in 1997 to 2.24/1,000 person-years in 2006, a 15.3% (95% CI=8.7-21.9) decrease. Among subjects aged 85 years or older, incidence rates for men declined from 27.0/1,000 to 18.9/1,000 person-years, and for women they declined from 32.7/1,000 to 27.1/1,000 person-years. CONCLUSION: Hip fracture incidence has been declining in all age groups over the past 10 years. While many factors may contribute to this decline, the results are consistent with a potential benefit of the active bone health intervention.

Surveillance of autoimmune conditions following routine use of quadrivalent human papillomavirus vaccine.

OBJECTIVE: An observational safety study of the quadrivalent human papillomavirus vaccine (HPV4) in women was conducted. This report presents findings from autoimmune surveillance. Design. Subjects were followed for 180days after each HPV4 dose for new diagnoses of 16 prespecified autoimmune conditions. SETTING: Two managed care organizations in California. Subjects. Number of 189,629 women who received ≥1 dose of HPV4 between 08/2006 and 03/2008. OUTCOME: Potential new-onset autoimmune condition cases amongst HPV4 recipients were identified by electronic medical records. Medical records of those with ≥12-month health plan membership prior to vaccination were reviewed by clinicians to confirm the diagnosis and determine the date of disease onset. The incidence of each autoimmune condition was estimated for unvaccinated women at one study site using multiple imputations and compared with that observed in vaccinated women. Incidence rate ratios (IRR) were calculated. Findings were reviewed by an independent Safety Review Committee (SRC). RESULTS: Overall, 1014 potential new-onset cases were electronically identified; 719 were eligible for case review; 31-40% were confirmed as new onset. Of these, no cluster of disease onset in relation to vaccination timing, dose sequence or age was found for any autoimmune condition. None of the estimated IRR was significantly elevated except Hashimoto's disease [IRR=1.29, 95% confidence interval: 1.08-1.56]. Further investigation of temporal relationship and biological plausibility revealed no consistent evidence for a safety signal for autoimmune thyroid conditions. The SRC and the investigators identified no autoimmune safety concerns in this study. CONCLUSIONS: No autoimmune safety signal was found in women vaccinated with HPV4.

Safety of zoster vaccine in adults from a large managed-care cohort: a Vaccine Safety Datalink study.

OBJECTIVES: The aim of this study was to examine a large cohort of adults who received the zoster vaccine for evidence of an increased risk of prespecified adverse events requiring medical attention. DESIGN: Two self-comparison approaches, including a case-centred approach and a self-controlled case series (SCCS) analysis were used. SETTING: Eight managed-care organizations participating in the Vaccine Safety Datalink project in the United States. SUBJECTS: A total of 193 083 adults aged 50 and older receiving a zoster vaccine from 1 January 2007 to 31 December 2008 were included. MAIN OUTCOME MEASURES: Prespecified adverse events were identified by aggregated International Classification of Diseases, Ninth Revision (ICD-9) codes in automated health plan datasets. RESULTS: The risk of allergic reaction was significantly increased within 1-7 days of vaccination [relative risk = 2.13, 95% confidence interval (CI): 1.87-2.40 by case-centred method and relative rate = 2.32, 95% CI: 1.85-2.91 by SCCS]. No increased risk was found for the following adverse event groupings: cerebrovascular events; cardiovascular events; meningitis; encephalitis; and encephalopathy; and Ramsay-Hunt syndrome and Bell's palsy. CONCLUSIONS: The results of this study support the findings from the prelicensure clinical trials, providing reassurance that the zoster vaccine is generally safe and well-tolerated with a small increased risk of allergic reactions in 1-7 days after vaccination.

Racial and ethnic disparities in diabetes risk after gestational diabetes mellitus.

AIMS/HYPOTHESIS: To investigate racial/ethnic disparities in diabetes risk after gestational diabetes mellitus (GDM). METHODS: This is a retrospective cohort study of women enrolled in the Kaiser Permanente Southern California health plan from 1995 to 2009. GDM status was identified on the basis of plasma glucose levels during pregnancy. The incidence of diabetes after the first delivery complicated by GDM before 31 December 2009 (n = 12,998) was compared with the experience for women without GDM (n = 64,668) matched on maternal age at delivery, race/ethnicity and year of delivery (1:5 ratio). Matched Cox regression was used to compare the RRs of diabetes associated with GDM within and across racial/ethnic groups. RESULTS: Compared with the women without GDM, the HRs (95% CI) of diabetes for women after GDM were 6.5 (5.2, 8.0) in non-Hispanic white, 7.7 (6.8, 8.7) in Hispanic, 9.9 (7.5, 13.1) in black and 6.3 (5.0, 7.9) in Asian/Pacific Islanders after adjustment for parity, maternal education, comorbidity and number of outpatient visits before the index pregnancy. The HR of diabetes for black women was significantly higher than that for non-Hispanic white women (p = 0.032). Further adjustment for prepregnancy BMI reduced the diabetes risk association with GDM for each racial/ethnic group, but did not explain the risk differences across groups. CONCLUSIONS/INTERPRETATIONS: Racial/ethnic disparities exist in risk of diabetes after GDM. Black women with GDM had the highest risk of developing diabetes. This highlights the importance of developing an effective diabetes screening and prevention programme in women with GDM, particularly black women with GDM.

Budget impact analysis of a new prostate cancer risk index for prostate cancer detection.

The objective of this study was to evaluate the budget impact of a new prostate cancer risk index for detecting prostate cancer. The index is calculated as the combination of serum prostate-specific antigen (PSA), free PSA and a precursor form p2PSA. We constructed two budget impact models using PSA cutoff values of ≥2 ng ml(-1) (model #1) and ≥4 ng ml(-1) (model #2) for recommending a prostate biopsy in a hypothetical health plan with 100 000 male members aged 50-75 years old. The budgetary impact on the 1-year expected total costs for prostate cancer detection was calculated. Adding the index to the current PSA prostate cancer testing strategies including the total PSA and percent free PSA, the number of detected cancer cases decreased by 20 and 5, in models #1 and #2, respectively. The savings on expected 1-year cost for prostate cancer detection were $356 647 (or $0.30 per-member-per-month (PMPM)) in model #1 and $94 219 ($0.08 PMPM) in model #2. The index produced higher cost savings in the model #1 with PSA cutoff ≥2 ng ml(-1) than the model #2 with cutoff ≥4 ng ml(-1) with a small short-term reduction in the number of positive tests.

Do cardiovascular risk factors confer the same risk for cardiovascular outcomes in rheumatoid arthritis patients as in non-rheumatoid arthritis patients?

OBJECTIVE: To compare the frequency of traditional cardiovascular (CV) risk factors in rheumatoid arthritis (RA) compared to non-RA subjects, and examine their impact on the risk of developing selected CV events (myocardial infarction (MI), heart failure (HF) and CV death) in these two groups. METHODS: We examined a population-based incidence cohort of subjects with RA (defined according to the 1987 American College of Rheumatology criteria), and an age- and sex-matched non-RA cohort. All subjects were followed longitudinally through their complete community medical records, until death, migration, or 1 January 2001. Clinical CV risk factors and outcomes were defined using validated criteria. The chi2 test was used to compare the frequency of each CV risk factor at baseline. Person-years methods were used to estimate the rate of occurrence of each CV risk factor during follow-up. Cox models were used to examine the influence of CV risk factors on the development of CV outcomes. RESULTS: A total of 603 RA and 603 non-RA subjects (73% female; mean age 58 years) were followed for a mean of 15 and 17 years (total: 8842 and 10,101 person-years), respectively. At baseline, RA subjects were significantly more likely to be former or current smokers when compared to non-RA subjects (p<0.001). Male gender, smoking, and personal cardiac history had weaker associations with CV events among RA subjects, compared to non-RA subjects. There was no significant difference between RA and non-RA subjects in the risk imparted with respect to the other CV risk factors (ie, family cardiac history, hypertension, dyslipidaemia, body mass index, or diabetes mellitus). CONCLUSION: While some traditional CV risk factors imparted similar risk among RA compared with non-RA subjects, others (ie, male gender, smoking and personal cardiac history) imparted significantly less risk for the development of CV disease. These differences in the overall impact of traditional CV risk factors suggest that strategies to prevent CV disease and mortality focused solely on controlling traditional CV risk factors may be relatively less beneficial in RA subjects than in the general population. Further research is needed to determine optimal approaches to reducing CV morbidity and mortality in persons with RA.

Raised erythrocyte sedimentation rate signals heart failure in patients with rheumatoid arthritis.

BACKGROUND: Inflammatory markers are associated with heart failure. Patients with rheumatoid arthritis have twice the risk of heart failure compared with people without rheumatoid arthritis. OBJECTIVE: To assess whether heart failure in patients with rheumatoid arthritis is preceded by an inflammatory activation as shown by erythrocyte sedimentation rate (ESR), a systemic marker of inflammation. METHODS: A population-based inception cohort of 575 patients with rheumatoid arthritis, free of heart failure at their rheumatoid arthritis incidence date, was followed up longitudinally until death or 2001. During 15 years of follow-up, they had a median of 15 ESR tests, and 172 patients had new-onset heart failure (Framingham Heart Study criteria). The follow-up period, beginning with the rheumatoid arthritis incidence date and ending with date of the last follow-up, was divided into 6-month intervals. The proportions of patients with at least one ESR value >/=40 mm/h and with anaemia (haemoglobin <11 g/dl) within each 6-month interval were plotted against time from fulfilment of heart failure criteria. A binomial test was used to compare proportions. RESULTS: In patients with rheumatoid arthritis who developed heart failure, the proportion with ESR >/=40 mm/h was highest (23%) during the 6-month period immediately preceding the new-onset heart failure, as compared with the average ESR during the entire remaining follow-up period, both before and after heart failure (10.6%; p<0.01). The proportion of patients with anaemia peaked (54%) during the 6-month period after heart failure. CONCLUSIONS: Inflammatory stimuli may be involved in the initiation of heart failure among patients with rheumatoid arthritis.

Correlations among measles virus-specific antibody, lymphoproliferation and Th1/Th2 cytokine responses following measles-mumps-rubella-II (MMR-II) vaccination.

Immunity to measles is conferred by the interplay of humoral and cellular immune responses, the latter being critical in maintaining long-term recall response. Therefore, it is important to evaluate measles-specific humoral and cellular immunity in populations several years after vaccination and understand the correlations among these measures of immunity. We examined measles-specific antibodies, lymphoproliferation and the Th1/Th2 signature cytokines, interferon (IFN)-gamma and interleukin (IL)-4, in a population-based cohort of healthy children from Olmsted County, Minnesota after two doses of measles-mumps-rubella-II (MMR-II) vaccine. We detected positive measures of measles-specific cellular and humoral immunity in the majority of our study population. However, a small proportion of subjects demonstrated an immune response skewed towards the Th2 type, characterized by the presence of either IL-4 and/or measles-specific antibodies and a lack of IFN-gamma production. Further, we observed a significant positive correlation between lymphoproliferation and secretion of IFN-gamma (r = 0.20, P = 0.0002) and IL-4 (r = 0.15, P = 0.005). Measles antibody levels were correlated with lymphoproliferation (r = 0.12, P = 0.03), but lacked correlation to either cytokine type. In conclusion, we demonstrated the presence of both long-term cellular and humoral responses after MMR-II vaccination in a significant proportion of study subjects. Further, a positive correlation between lymphoproliferation and IL-4 and IFN-gamma suggests that immunity to measles may be maintained by both Th1 and Th2 cells. We speculate that the Th2 biased response observed in a subset of our subjects may be insufficient to provide long-term immunity against measles. Further examination of the determinants of Th1 versus Th2 skewing of the immune response and long-term follow-up is needed.

Disease modifying strategies for the treatment of Alzheimer's disease targeted at modulating levels of the beta-amyloid peptide.

AD (Alzheimer's disease) is characterized neuropathologically by the presence of amyloid plaques, neurofibrillary tangles and profound grey matter loss. The 'amyloid' hypothesis postulates that the toxic Abeta (amyloid beta) peptide, enzymatically derived from the proteolytic processing of a larger protein called APP (amyloid precursor protein), is one of the principal causative factors of neuronal cell death in the brains of AD patients. As such, methods for lowering Abeta levels in the brain are of significant interest with regard to identifying novel disease modifying therapies for the treatment of AD. In this review, we will review a variety of approaches and mechanisms capable of modulating levels of Abeta.

Distribution of the Brief Male Sexual Inventory in community men.

The objectives of the study were to characterize male sexual functioning as related to age in community-dwelling older men. In 1989, a random sample of men aged 40-79 y (n=2115) without prior prostate surgery, prostate cancer, or other conditions known to affect voiding function (except benign prostatic hyperplasia) was invited (55% agreed) to participate in the Olmsted County Study of Urinary Symptoms and Health Status Among Men. In 1996, a previously validated male sexual function questionnaire was administered to the cohort. The questionnaire has 11 questions measuring sexual drive (two questions); erectile function (three) and ejaculatory function (two), as well as assessing problems with sex drive, erections, or ejaculation (three); and overall satisfaction with sex life (one). Each question is scored on a scale of 0-4, with higher scores indicating better functioning. Cross-sectional age-specific means (+/-s.d.) for drive, erections, ejaculation, problems, and overall satisfaction declined from 5.2 (+/-1.5), 9.8 (+/-2.5), 7.4 (+/-1.4), 10.7 (+/-2.2), and 2.6 (+/-1.0), respectively, for men in their 40s to 2.4 (+/-1.6), 3.3 (+/-3.4), 3.6 (+/-3.2), 7.7 (+/-3.8), and 2.1 (+/-1.2) for men 70 y and older (all P<0.001). The cross-sectional decline in function with age was not constant, with age-related patterns differing by domain. The percentage of men reporting erections firm enough to have intercourse in the past 30 days declined from 97% (454/468) among those in their 40s to 51% (180/354) among those in their 80s (P&<0.001). In age-adjusted analyses, men reporting regular sexual partners had statistically significantly higher levels of sex drive, erectile function, ejaculatory function, and overall satisfaction than those who did not report regular sexual partners. Sexual drive, erectile functioning, ejaculatory functioning, and overall sexual satisfaction in men show somewhat differing cross-sectional patterns of decline with advancing age. Active sexual functioning is maintained well into the 80s in a substantial minority of community-dwelling men.

Lack of association between transporter associated with antigen processing (TAP) and HLA-DM gene polymorphisms and antibody levels following measles vaccination.

The transporter associated with antigen processing (TAP) and human leukocyte antigen-DM (HLA-DM) genes are involved in the antigen-processing pathway of both HLA class I and class II-restricted antigen presentation. We hypothesized that polymorphisms within the TAP and DM genes may influence antibody levels following measles vaccination. We examined TAP and DM polymorphisms in 242 school children from Olmsted County, Minnesota, USA who received one dose of measles-mumps-rubella-II (MMR-II) vaccine at the age of 15 months. Based on the level of serum measles-specific immunoglobulin G (IgG) antibodies, subjects were classified as seronegatives (n = 72) or seropositives (n = 170). We determined TAP1 and TAP2 allele types by polymerase chain reaction (PCR) amplification of specific alleles (PASA) and determined DM allele type by PCR amplification followed by direct sequencing of the polymorphic sites. We analysed the data for any TAP or DM allelic association with antibody levels post measles vaccination using the chi-square test and univariate linear regression analysis. We found no trend in the overall distribution of TAP and DM genotype frequencies between seronegative and seropositive subjects, suggesting that TAP and DM polymorphism and antibody levels following measles vaccination are not directly associated. In addition, we did not find an association between TAP (TAP1, P = 0.71; TAP2, P = 0.87) or DM (DMA, P = 0.42; DMB, P = 0.71) homozygosity and seronegativity to measles vaccine in this study group. Our study suggests that TAP and DM gene polymorphisms do not influence antibody levels post measles vaccination.

Incidence of physician-diagnosed interstitial cystitis in Olmsted County: a community-based study.

OBJECTIVE: To obtain community-based information about the incidence of interstitial cystitis, a chronic disabling condition of the bladder where knowledge is limited because there are no definitive diagnostic criteria. PATIENTS AND METHODS: All residents of Olmsted County, MN, USA who had received a physician-assigned diagnosis of interstitial cystitis between 1976 and 1996 were identified through the resources of the Rochester Epidemiology Project. The clinical findings at diagnosis and during the follow-up were ascertained from the community medical records for each study subject. RESULTS: In all, 16 women and four men received a diagnosis of interstitial cystitis during the study period. The overall age- and sex-adjusted (95% confidence interval) incidence rate was 1.1 (0.6-1.5) per 100 000 population. The age-adjusted incidence rates were 1.6 per 100 000 in women and 0.6 per 100 000 in men (P = 0.04). The median (range) age at initial diagnosis was 44.5 (27-76) years in women and 71.5 (23-79) years in men (P = 0.26). The median number of episodes of care-seeking for symptoms before the diagnosis was one for women and 4.5 for men (P = 0.03). The median duration from the onset of symptoms until the first diagnosis was 0.06 and 2.2 years in women and men, respectively (P = 0.2). CONCLUSIONS: These findings suggest that the incidence of interstitial cystitis in the community is extremely low. Although the gender difference may be real, the trend toward a later diagnosis in men than in women suggests a potential for missed diagnosis in men. This might explain some of the gender difference in the incidence of interstitial cystitis in men and women.

Natural history of benign prostatic hyperplasia.

Studies in varied settings have provided estimates of the prevalence of surrogate markers of benign prostatic hyperplasia (BPH). In population-based studies, the prevalence of moderate-to-severe lower urinary tract symptoms and depressed peak urinary flow rates increases across successively older age groups. Prostatic volume follows a similar pattern. Unlike clinic-based studies in which correlations are almost nonexistent, the population-based studies demonstrate a modest correlation among lower urinary tract symptoms, peak urinary flow rates, and prostatic volume. These cross-sectional observations extend to serum prostate-specific antigen levels and postvoid residual urine volumes. Data collected during the longitudinal follow-up study of men participating in the Olmsted County Study of Urinary Symptoms and Health Status Among Men provide a more detailed description of the natural history of changes in these surrogate markers of BPH. They also provide insights into their relation with each other and with long-term outcomes of BPH, such as acute urinary retention and treatment of BPH. These data demonstrate the progressive nature of BPH and are useful for the design and interpretation of clinical trials. Furthermore, they suggest that observational studies of etiology and prognosis should take advantage of the spectrum of disease reflected by the full range of values of these quantitative traits, rather than an arbitrary dichotomized outcome.

Prostate volume and prostate-specific antigen in the absence of prostate cancer: a review of the relationship and prediction of long-term outcomes.

BACKGROUND: The risk for long-term outcomes associated with benign prostatic hyperplasia (BPH) has not been well characterized. Untreated, BPH can lead to complications and negative outcomes, such as deterioration of bladder function, urinary tract infection, acute urinary retention (AUR), and surgery. METHODS: A literature review was conducted to summarize the results of studies investigating the relationship of prostate volume and PSA with prediction of long-term outcomes in the absence of prostate cancer. RESULTS: In the studies reviewed, men with moderate to severe symptoms, depressed uroflow, prostatic enlargement and elevated PSA were at greater risk for developing subsequent AUR or surgery. Men with prostatic enlargement had a 3-fold higher risk for acute urinary retention and were 4 times more likely to have had any treatment for BPH. CONCLUSIONS: The results of these studies may assist physicians in discussing treatment options as well as long-term complications with patients.

Incidence of reading disability in a population-based birth cohort, 1976-1982, Rochester, Minn.

OBJECTIVE: To report the incidence of reading disability among school-aged children. SUBJECTS AND METHODS: In this population-based, retrospective birth cohort study, subjects included all 5718 children born between 1976 and 1982 who remained in Rochester, Minn, after the age of 5 years. Based on records from all public and nonpublic schools, medical facilities, and private tutorial services and on results of all individually administered IQ and achievement tests, extensive medical, educational, and socioeconomic information were abstracted. Reading disability was established with use of research criteria based on 4 formulas (2 regression-based discrepancy, 1 non-regression-based discrepancy, and 1 low achievement). RESULTS: Cumulative incidence rates of reading disability varied from 5.3% to 11.8% depending on the formula used. Boys were 2 to 3 times more likely to be affected than girls, regardless of the identification methods applied. CONCLUSIONS: In this population-based birth cohort, reading disability was common among school-aged children and significantly more frequent among boys than girls, regardless of definition.

Boy/girl differences in risk for reading disability: potential clues?

The authors conducted a case-control study to determine whether risk factors for reading disability (RD) differentially affect boys and girls. The study population included all children born between 1976 and 1982 in Olmsted County, Minnesota (n = 5,701). A total of 303 RD cases were identified by using intelligence quotient and achievement test scores collected from school and medical records. After excluding those who met exclusion criteria (n = 869), controls consisted of all children not identified with RD (n = 4,529). The authors examined the association between RD and potential risk factors in boys and girls and confirmed their results in multivariable logistic regression models. Multivariable models indicated that girls of low birth weight were more than twice as likely to be identified as RD (odds ratio (OR) = 2.94, 95% confidence interval (CI): 1.09, 6.25). Girls whose mothers had 12 or fewer years of education were twice as likely to be identified as RD (OR = 2.14, 95% CI: 1.24, 3.72). However, girls whose fathers were aged 35 years or older at the time of birth were less likely to be identified as RD (OR = 0.24, 95% CI: 0.06, 0.92). Only 12 or fewer years of paternal education was associated with increased RD in boys (OR = 2.28, 95% CI: 1.59, 3.27). Boys and girls appear to be differentially susceptible to RD risk factors, suggesting that the biologic processes leading to RD may differ between boys and girls.