Association of hearing impairment with brain volume changes in older adults

Hearing impairment in older adults is independently associated in longitudinal studies with accelerated cognitive decline and incident dementia, and in cross-sectional studies, with reduced volumes in the auditory cortex. Whether peripheral hearing impairment is associated with accelerated rates of brain atrophy is unclear. We analyzed brain volume measurements from magnetic resonance brain scans of individuals with normal hearing versus hearing impairment (speech-frequency pure tone average>25 dB) followed in the neuroimaging substudy of the Baltimore Longitudinal Study of Aging for a mean of 6.4 years after the baseline scan (n=126, age 56-86 years). Brain volume measurements were performed with semi-automated region-of-interest (ROI) algorithms, and brain volume trajectories were analyzed with mixed-effect regression models adjusted for demographic and cardiovascular factors. We found that individuals with hearing impairment (n=51) compared to those with normal hearing (n=75) had accelerated volume declines in whole brain and regional volumes in the right temporal lobe (superior, middle, and inferior temporal gyri, parahippocampus, p<.05). These results were robust to adjustment for multiple confounders and were consistent with voxel-based analyses, which also implicated right greater than left temporal regions. These findings demonstrate that peripheral hearing impairment is independently associated with accelerated brain atrophy in whole brain and regional volumes concentrated in the right temporal lobe. Further studies investigating the mechanistic basis of the observed associations are needed.

Glucose intolerance, insulin resistance, and pathological features of Alzheimer disease in the Baltimore Longitudinal Study of Aging

IMPORTANCE

Peripheral glucose homeostasis has been implicated in the pathogenesis of Alzheimer disease (AD). The relationship among diabetes mellitus, insulin, and AD is an important area of investigation. However, whether cognitive impairment seen in those with diabetes is mediated by excess pathological features of AD or other related abnormalities, such as vascular disease, remains unclear.

OBJECTIVE

To investigate the association between serial measures of glucose intolerance and insulin resistance and in vivo brain β-amyloid burden, measured with carbon 11–labeled Pittsburgh Compound B (11C-PiB), and AD pathology at autopsy.

DESIGN

Scores calculated from the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) and Braak criteria were correlated with measures of hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance in 197 participants who underwent autopsy after death and who had undergone 2 or more oral glucose tolerance tests (OGTT) using grouped analyses and a continuous mixed-models analysis. The same measures of glucose intolerance and insulin resistance were also correlated with brain 11C-PiB retention in an additional 53 living subjects from the Baltimore Longitudinal Study of Aging neuroimaging study.

SETTING

Prospective, serially assessed cohort of community-dwelling subjects.

PARTICIPANTS

Cohort 1 consisted of 197 participants enrolled in the Baltimore Longitudinal Study of Aging who had 2 or more OGTTs during life and a complete brain autopsy after death. Cohort 2 consisted of 53 living subjects who had 2 or more OGTTs and underwent brain 11C-PiB positron emission tomography.

EXPOSURES

Autopsy and 11C-PiB positron emission tomography.

MAIN OUTCOMES AND MEASURES

The correlation of brain markers of AD, including CERAD score, Braak score, and 11C-PiB retention, with serum markers of glucose homeostasis using grouped and continuous mixed-models analyses.

RESULTS

We found no significant correlations between measures of brain AD pathology or 11C-PiB β-amyloid load and glucose intolerance or insulin resistance in subjects who had a mean (SD) of 6.4 (3.2) OGTTs during 22.1 (8.0) years of follow-up. Thirty subjects with frank diabetes mellitus who received medications also had AD pathology scores that were similar to those of the cohort as a whole.

CONCLUSIONS AND RELEVANCE

In this prospective cohort with multiple assessments of glucose intolerance and insulin resistance, measures of glucose and insulin homeostasis are not associated with AD pathology and likely play little role in AD pathogenesis. Long-term therapeutic trials are important to elucidate this issue.

Performance on five times sit-to-stand task as a predictor of subsequent falls and disability in older persons

OBJECTIVE

To investigate whether the performance on 5 times sit-to-stand test (5tSTS) can predict subsequent falls, fall-related fracture, and activities of daily living (ADL) and instrumental activities of daily living (IADL) disability in older persons.

METHODS

A total of 948 older adults (age ≥ 60) participated in this study. Ability and the time to finish 5tSTS were recorded at baseline. Number of falls, fall-related fractures, and the ability to complete ADL and IADL without assistance were recorded retrospectively at baseline and at the 3-year follow-up.

RESULTS

Inability to complete 5tSTS was a marginal predictor of falls (OR = 4.22) and a significant predictor of ADL- (OR = 24.70) and IADL-related disability (OR = 17.10) at 3-year follow-up. The need of longer time to complete 5tSTS was predictive of developing IADL-related disability at 3-year follow-up (OR = 4.22 [> 16.6 s]; OR = 2.49 [13.7 - 16.6 s]).

DISCUSSION

5tSTS is an easily administered tool which can be used to predict subsequent ADL- and IADL-related disability.

Personality typology in relation to muscle strength

BACKGROUND

Physical inactivity plays a central role in the age-related decline in muscle strength, an important component in the process leading to disability. Personality, a significant determinant of health behaviors including physical activity, could therefore impact muscle strength throughout adulthood and affect the rate of muscle strength decline with aging. Personality typologies combining "high neuroticism" (N ≥ 55), "low extraversion" (E < 45), and "low conscientiousness" (C < 45) have been associated with multiple risky health behaviors but have not been investigated with regards to muscle strength.

PURPOSE

The purpose of this study is to investigate associations between individual and combined typologies consisting of high N, low E, and low C and muscle strength, and whether physical activity and body mass index act as mediators.

METHOD

This cross-sectional study includes 1,220 participants from the Baltimore Longitudinal Study of Aging.

RESULTS

High N was found among 18%, low E among 31%, and low C among 26% of the sample. High levels of N, particularly when combined with either low E or low C, were associated with lower muscle strength compared with having only one or none of these personality types. Facet analyses suggest an important role for the N components of depression and hostility. Physical activity level appears to partly explain some of these associations.

CONCLUSION

Findings provide support for the notion that the typological approach to personality may be useful in identifying specific personality types at risk of low muscle strength and offer the possibility for more targeted prevention and intervention programs.

Age-associated gait patterns and the role of lower extremity strength - results from the Baltimore Longitudinal Study of Aging

The aim of the present study was to examine differences in gait characteristics across the adult lifespan and to test the hypothesis that such differences are attributable at least in part to the decline in muscle strength. The data presented here are from 190 participants of the Baltimore Longitudinal Study of Aging (BLSA) aged from 32 to 93 years. Based on two age thresholds that best capture the effect of age on walking speed, participants were divided into three age groups: middle-age (32-57 years; N=27), old-age (58-78 years; N=125), and oldest-age (79-93 years; N=38). Participants were asked to walk at their preferred and maximum speeds while recorded with 3D gait analysis system. In addition, maximum isokinetic knee extensor strength was assessed. While walking at preferred speed, range of motion (ROM) and mechanical work expenditure (MWE) of the ankle were lower within middle-age (p<0.001, p=0.047, respectively), while hip ROM and MWE were lower (p=0.006) and higher (p<0.001), respectively within oldest-age with older age. Deterioration in ankle function during customary walking initiates already at middle-age. Differences in the maximum walking speed and ankle ROM between middle-age and old-age were explained by knee strength.

Associations between personality traits, physical activity level, and muscle strength

Associations among personality as measured by the Five Factor Model, physical activity, and muscle strength were assessed using data from the Baltimore Longitudinal Study of Aging (N = 1220, age: mean = 58, SD = 16). General linear modeling with adjustment for age, sex, race, and body mass index, and bootstrapping for mediation were used. We found neuroticism and most of its facets to negatively correlate with strength. The extraversion domain and its facets of warmth, activity, and positive-emotions were positively correlated with strength, independent of covariates. Mediation analysis results suggest that these associations are partly explained by physical activity level. Findings extend the evidence of an association between personality and physical function to its strength component and indicate health behavior as an important pathway.

Screening for prostate cancer using multivariate mixed-effects models

Using several variables known to be related to prostate cancer, a multivariate classification method is developed to predict the onset of clinical prostate cancer. A multivariate mixed-effects model is used to describe longitudinal changes in prostate specific antigen (PSA), a free testosterone index (FTI), and body mass index (BMI) before any clinical evidence of prostate cancer. The patterns of change in these three variables are allowed to vary depending on whether the subject develops prostate cancer or not and the severity of the prostate cancer at diagnosis. An application of Bayes' theorem provides posterior probabilities that we use to predict whether an individual will develop prostate cancer and, if so, whether it is a high-risk or a low-risk cancer. The classification rule is applied sequentially one multivariate observation at a time until the subject is classified as a cancer case or until the last observation has been used. We perform the analyses using each of the three variables individually, combined together in pairs, and all three variables together in one analysis. We compare the classification results among the various analyses and a simulation study demonstrates how the sensitivity of prediction changes with respect to the number and type of variables used in the prediction process.

Selective contribution of regional adiposity, skeletal muscle, and adipokines to glucose disposal in older adults

OBJECTIVES

To study the relationships between muscle mass, regional adiposity, and adipokines and glucose disposal in an older population.

DESIGN

Cross-sectional analysis.

SETTING

Community-dwelling volunteers from the Baltimore Longitudinal Study of Aging.

PARTICIPANTS

Two hundred eighty men and 259 women with a mean age of 71.1 ± 0.4 (range 55-96) and complete data on fasting plasma adiponectin and leptin, oral glucose tolerance test (OGTT) (plasma glucose available at 0, 20, 40, 60, 80, 100, and 120 minutes), thigh computed tomography (CT), physical activity levels, and anthropometric measures.

MEASUREMENTS

Participants were classified into eight groups according to the presence of global adiposity (body mass index > 27 kg/m(2)), central adiposity (waist circumference > 88 cm for women and > 102 cm for men), and low muscle mass (CT thigh, lowest sex-specific tertile (93.8 cm(2) in women and 110.7 cm(2) in men) of adjusted thigh muscle area). Linear regression models were used to estimate the contribution of these eight groups to early glucose area under the curve (AUC) (t = 0-40 minutes), late glucose AUC (t = 60-120 minutes), and total glucose AUC (t = 0-120 minutes) from the OGTT.

RESULTS

Regardless of muscle mass, individuals with a combination of central and global adiposity were more likely to have delayed glucose disposal rates (P < .05). A strong negative association was also found between circulating adiponectin levels and glucose disposal rates (early AUC, β = -0.14; late AUC, β = -0.20; and total AUC, β = -0.20; P < .05 for all three AUCs) after adjusting for regional adiposity, muscle mass, circulating leptin levels, physical activity, age, and sex.

CONCLUSION

Older individuals with global and central adiposity may be at risk of glucose intolerance unrelated to low muscle mass.

Prostate-specific antigen velocity (PSAV) risk count improves the specificity of screening for clinically significant prostate cancer

OBJECTIVE

•  To determine whether the prostate-specific antigen velocity (PSAV) risk count (i.e. the number of times PSAV exceeds a specific threshold) could increase the specificity of screening for prostate cancer and potentially life-threatening tumours.

PATIENTS AND METHODS

•  From 1989 to 2001, we calculated two serial PSAV measurements in 18 214 prostate cancer screening-study participants, of whom 1125 (6.2%) were diagnosed with prostate cancer. •  The PSAV risk count was determined as the number of PSAV measurements of >0.4 ng/mL/year (0, 1, or 2). •  We used receiver operating characteristic (ROC) and reclassification analyses to examine the ability of PSAV risk count to predict screen-detected and high-grade prostate cancer.

RESULTS

•  The PSAV was >0.4 ng/mL/year twice (risk count 2) in 40% of prostate cancer cases compared with only 4% of those with no cancer (P < 0.001). •  After adjusting for age and PSA level, a PSAV risk count of 2 was associated with an 8.2-fold increased risk of prostate cancer (95% confidence interval 7.0-9.6, P < 0.001) and 5.4-fold increased risk of Gleason score 8-10 prostate cancer on biopsy. •  Compared with a model with age and PSA level, the addition of the PSAV risk count significantly improved discrimination (area under the ROC curve 0.625 vs 0.725, P= 0.031) and reclassified individuals for the risk of high-grade prostate cancer (net reclassification, P < 0.001).

CONCLUSIONS

•  Sustained rises in PSA indicate a significantly greater risk of prostate cancer, particularly high-grade disease. •  Compared with men with a risk count of ≤1, those with two PSAV measurements of >0.4 ng/mL/year (risk count 2) had an 8-fold increased risk of prostate cancer and 5.4-fold increased risk of Gleason 8-10 disease on biopsy, adjusting for age and PSA level. •  Compared to PSA alone, PSAV risk count may be useful in reducing unnecessary biopsies and the diagnosis of low-risk prostate cancer.

The relationship between prostate volume and prostate-specific antigen variability: data from the Baltimore Longitudinal Study of Aging and the Johns Hopkins Active Surveillance Program

Study Type--Prognostic (cohort). Level of Evidence 2b. What's known on the subject? And what does the study add? Previous studies have attempted to characterize the normal biological variability in PSA among men without prostate cancer. These reports suggest that PSA variability is unrelated to age, but there are conflicting data on its association with the baseline PSA level. There are limited published data regarding the effects of prostate volume on PSA variability. A prior study assessing whether prostate volume changes would confound the use of PSA velocity in clinical practice reported that prostate volume changes were not significantly related to PSA changes. This study did not directly address the effect of baseline prostate volume on serial PSA variability. The objective of the current study was to further examine the relationship between prostate volume and PSA variability. Our hypothesis was that larger baseline prostate volume would be associated with increased PSA variability in men without known prostate cancer and in those with suspected small-volume disease. The results of the study suggest that baseline PSA, not prostate volume, is the primary driver of PSA variability in these populations.

OBJECTIVE

• To clarify the relationship between serial prostate-specific antigen (PSA) variability and prostate volume in both cancer-free participants from the Baltimore Longitudinal Study of Aging (BLSA) and patients with low-risk prostate cancer from the Johns Hopkins Active Surveillance Program (AS).

MATERIALS AND METHODS

• In all, 287 men from the BLSA and 131 patients from the AS were included in the analysis, all with at least two PSA measurements and concurrent prostate volume measurements. • PSA variability was calculated in ng/mL per year, and a linear mixed-effects model was used to determine the relative effects of prostate volume, baseline PSA and age on PSA change over time.

RESULTS

• In a model with prostate volume, age and baseline PSA, there was no significant relationship between prostate volume and PSA variability (BLSA, P= 0.57; AS, P= 0.49). • Only baseline PSA showed a significant relationship to PSA yearly variability (PSAYV) (P < 0.001). Specifically, a one unit higher baseline PSA (ng/mL) corresponded on average to 0.09 and 0.06 ng/mL per year higher PSAYV in the BLSA and AS populations, respectively.

CONCLUSIONS

• The results of the present study suggest that the primary driver of PSA variability is the baseline PSA level, rather than prostate volume. • Clinicians might consider the baseline PSA level to help predict the expected variability in serial PSA measurements.

Hearing loss and cognition in the Baltimore Longitudinal Study of Aging

OBJECTIVE

To determine the relationship between hearing loss and cognitive function as assessed with a standardized neurocognitive battery. We hypothesized a priori that greater hearing loss is associated with lower cognitive test scores on tests of memory and executive function.

METHOD

A cross-sectional cohort of 347 participants ≥ 55 years in the Baltimore Longitudinal Study of Aging without mild cognitive impairment or dementia had audiometric and cognitive testing performed in 1990-1994. Hearing loss was defined by an average of hearing thresholds at 0.5, 1, 2, and 4 kHz in the better-hearing ear. Cognitive testing consisted of a standardized neurocognitive battery incorporating tests of mental status, memory, executive function, processing speed, and verbal function. Regression models were used to examine the association between hearing loss and cognition while adjusting for confounders.

RESULTS

Greater hearing loss was significantly associated with lower scores on measures of mental status (Mini-Mental State Exam), memory (Free Recall), and executive function (Stroop Mixed, Trail Making B). These results were robust to analyses accounting for potential confounders, nonlinear effects of age, and exclusion of individuals with severe hearing loss. The reduction in cognitive performance associated with a 25 dB hearing loss was equivalent to the reduction associated with an age difference of 6.8 years.

CONCLUSION

Hearing loss is independently associated with lower scores on tests of memory and executive function. Further research examining the longitudinal association of hearing loss with cognitive functioning is needed to confirm these cross-sectional findings.

A pedometer-based intervention to improve physical activity, fitness, and coronary heart disease risk in National Guard personnel

To compare the effects of a pedometer-based behavioral intervention (Fitness for Life [FFL] program) and a traditional high-intensity fitness (TRAD) program on physical activity (PA), Army Physical Fitness Test (APFT), and coronary heart disease risk factors in Army National Guard members who failed the APFT 2-mile run. From a pool of 261 Army National Guard, a total of 156 were randomized to TRAD or FFL for 24 weeks consisting of a 12-week progressive conditioning program followed by 12 weeks of maintenance. For both groups, the total APFT score and 2-mile run time/score improved from baseline to 12 weeks (FFL: down 7.4%, p = 0.03; TRAD: down 5%, p = 0.08) but at 24 weeks they had regressed toward baseline. PA improved modestly and coronary risk profile changed minimally in both groups. A pedometer-based exercise intervention had results similar to a high-intensity program for improving PA, APFT, and 2-mile run times/score. Neither group sustained the improved run times over the 12 weeks of maintenance.

Sensorimotor and psychosocial correlates of adaptive locomotor performance in older adults

OBJECTIVE

To identify sensorimotor and psychosocial factors independently associated with an inability to perform adaptive walking tasks in older adults.

DESIGN

Cross-sectional cohort study.

SETTING

Population-based older cohort.

PARTICIPANTS

Community-living elderly (N=720; age ≥65y) who could walk 7m at self-selected normal speed.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Walking performance was assessed in 4 walking tests: fast walking, obstacle crossing, narrow-based walking, and walking while talking. Possible correlates of the inability to perform the walking test included knee extensor strength, lower limb coordination, Cumulative Somatosensory Impairment Index (CSII), visual acuity and contrast sensitivity, cognition, depression, personal mastery, social support, and years of education.

RESULTS

The results of binary logistic regression analyses, adjusted for demographics and self-selected normal speed, demonstrated that poor knee extensor strength was associated with an inability to perform tasks demanding an increase in walking speed (fast walking and obstacle crossing). Both poor lower limb coordination and higher CSII were significantly associated with failure in tests that demanded precise control over foot placement (obstacle crossing and narrow-based walking). Higher CSII was associated with failure in all tests except in the walking while talking. In contrast, poor cognition was associated with an inability to perform walking while talking. Poor personal mastery was the only variable that was associated with failure in all walking tests.

CONCLUSIONS

The results demonstrated a systematic and coherent pattern in these associations and indicated possible sensorimotor and psychological parameters that should be specifically investigated and should be intervened if a patient reports a difficulty/inability in walking in certain situations.

Cross-sectional evidence of a signaling pathway from bone homeostasis to glucose metabolism

CONTEXT

Preclinical studies suggested the existence of a signaling pathway connecting bone and glucose metabolisms. Supposedly leptin modulates osteocalcin bioactivity, which in turn stimulates insulin and adiponectin secretion, and β-cell proliferation.

OBJECTIVE

The objective of the investigation was to study the reciprocal relationships of adiponectin, leptin, osteocalcin, insulin resistance, and insulin secretion to verify whether such relationships are consistent with a signaling pathway connecting bone homeostasis and glucose metabolism.

DESIGN

This was a cross-sectional analysis.

SETTING

The study was conducted with community-dwelling volunteers participating in the Baltimore Longitudinal Study of Aging.

PARTICIPANTS

Two hundred eighty women and 300 men with complete data on fasting plasma adiponectin, leptin, and osteocalcin, oral glucose tolerance test (plasma glucose and insulin values available at t = 0, 20, and 120 min), and anthropometric measures participated in the study.

MAIN OUTCOME MEASURES

Linear regression models were used to test independent associations of adiponectin, osteocalcin, and leptin with the indices of insulin resistance and secretion. The expected reciprocal relationship between different biomarkers was verified by structural equation modeling.

RESULTS

In linear regression models, leptin was strongly associated with indices of both insulin resistance and secretion. Both adiponectin and osteocalcin were negatively associated with insulin resistance. Structural equation modeling revealed a direct inverse association of leptin with osteocalcin; a direct positive association of osteocalcin with adiponectin; and an inverse relationship of osteocalcin with insulin resistance and adiponectin with insulin resistance and secretion, which is cumulatively consistent with the hypothesized model.

CONCLUSIONS

Bone and glucose metabolisms are probably connected through a complex pathway that involves leptin, osteocalcin, and adiponectin. The clinical relevance of such a pathway for bone pathology in diabetes should be further investigated.

Relationship between plasma ghrelin, insulin, leptin, interleukin 6, adiponectin, testosterone and longevity in the Baltimore Longitudinal Study of Aging

BACKGROUND AND AIMS

Caloric restriction (CR) is the most robust and reproducible intervention for slowing aging, and maintaining health and vitality in animals. Previous studies found that CR is associated with changes in specific biomarkers in monkeys that were also associated with reduced risk of mortality in healthy men. In this study we examine the association between other potential biomarkers related to CR and extended lifespan in healthy humans.

METHODS

Based on the Baltimore Longitudinal Study of Aging, "long-lived" participants who survived to at least 90 years of age (n=41, cases) were compared with "short-lived" participants who died between 72-76 years of age (n=31, controls) in the nested case control study. Circulating levels of ghrelin, insulin, leptin, interleukin 6, adiponectin and testosterone were measured from samples collected between the ages 58 to 70 years. Baseline differences between groups were examined with t-test or Wilcoxon test, and mixed effects general linear model was used for a logistic model to differentiate the two groups with multiple measurements on some subjects.

RESULTS

At the time of biomarkers evaluation (58-70 yrs), none of the single biomarker levels was significantly different between the two groups. However, after combining information from multiple biomarkers by adding the z-transformed values, the global score differentiated the long- and short-lived participants (p=0.05).

CONCLUSIONS

In their sixties, long-lived and short-lived individuals do not differ in biomarkers that have been associated with CR in animals. However, difference between the groups was only obtained when multiple biomarker dysregulation was considered.

Glucose and insulin measurements from the oral glucose tolerance test and relationship to muscle mass

BACKGROUND

Diabetes is associated with decreased muscle mass. The effect of higher levels of glucose and insulin on muscle mass has not been studied in individuals without diabetes. We sought to determine the relationship of insulin and glucose measurements from the oral glucose tolerance test (OGTT) with muscle mass in persons without diabetes.

METHODS

We analyzed data from 587 participants in the Baltimore Longitudinal Study of Aging (mean age 67.3 years, range 26-95 years) without diabetes who underwent a 2-hour OGTT, including glucose and insulin measurements taken every 20 minutes and assessment of midthigh muscle cross-sectional area by computed tomography, taken as a proxy measure of muscle mass. Linear regression models and Bayesian model averaging were used to explore the independent cross-sectional association of various OGTT-derived measures and midthigh muscle cross-sectional area, independent of confounders.

RESULTS

Individually, fasting glucose, fasting insulin, OGTT glucose (40, 60, 80, 100, and 120 minutes), OGTT insulin (20, 60, 80, 100, and 120 minutes), homeostasis model assessment of insulin resistance, integrated glucose area, and integrated insulin area were inversely associated, and the Matsuda index was positively associated, with the midthigh muscle cross-sectional area (standardized to body weight) after adjustment for age, sex, race, height, physical activity, and peroneal motor nerve conduction velocity (all ps <.05). When considered together, the Matsuda index and fasting glucose were the strongest predictors of lower midthigh muscle cross-sectional area after covariate adjustment.

CONCLUSIONS

Higher fasting and OGTT values of both glucose and insulin are associated with lower muscle mass. Longitudinal studies are needed to verify whether individuals free of diabetes that have higher glucose and insulin during an OGTT are at risk for accelerated muscle mass decline with aging.

What is the true number needed to screen and treat to save a life with prostate-specific antigen testing?

PURPOSE

The European Randomized Study of Screening for Prostate Cancer (ERSPC) reported a 20% mortality reduction with prostate-specific antigen (PSA) screening. However, they estimated a number needed to screen (NNS) of 1,410 and a number needed to treat (NNT) of 48 to prevent one prostate cancer death at 9 years. Although NNS and NNT are useful statistics to assess the benefits and harms of an intervention, in a survival study setting such as the ERSPC, NNS and NNT are time specific, and reporting values at one time point may lead to misinterpretation of results. Our objective was to re-examine the effect of varying follow-up times on NNS and NNT using data extrapolated from the ERSPC report.

MATERIALS AND METHODS

On the basis of published ERSPC data, we modeled the cumulative hazard function using a piecewise exponential model, assuming a constant hazard of 0.0002 for the screening and control groups for years 1 to 7 of the trial and different constant rates of 0.00062 and 0.00102 for the screening and control groups, respectively, for years 8 to 12. Annualized cancer detection and drop-out rates were also approximated based on the observed number of individuals at risk in published ERSPC data.

RESULTS

According to our model, the NNS and NNT at 9 years were 1,254 and 43, respectively. Subsequently, NNS decreased from 837 at year 10 to 503 at year 12, and NNT decreased from 29 to 18.

CONCLUSION

Despite the seemingly simplistic nature of estimating NNT, there is widespread misunderstanding of its pitfalls. With additional follow-up in the ERSPC, if the mortality difference continues to grow, the NNT to save a life with PSA screening will decrease.

Hearing loss and incident dementia

OBJECTIVE

To determine whether hearing loss is associated with incident all-cause dementia and Alzheimer disease (AD).

DESIGN

Prospective study of 639 individuals who underwent audiometric testing and were dementia free in 1990 to 1994. Hearing loss was defined by a pure-tone average of hearing thresholds at 0.5, 1, 2, and 4 kHz in the better-hearing ear (normal, <25 dB [n = 455]; mild loss, 25-40 dB [n = 125]; moderate loss, 41-70 dB [n = 53]; and severe loss, >70 dB [n = 6]). Diagnosis of incident dementia was made by consensus diagnostic conference. Cox proportional hazards models were used to model time to incident dementia according to severity of hearing loss and were adjusted for age, sex, race, education, diabetes mellitus, smoking, and hypertension.

SETTING

Baltimore Longitudinal Study of Aging.

PARTICIPANTS

Six hundred thirty-nine individuals aged 36 to 90 years.

MAIN OUTCOME MEASURE

Incident cases of all-cause dementia and AD until May 31, 2008.

RESULTS

During a median follow-up of 11.9 years, 58 cases of incident all-cause dementia were diagnosed, of which 37 cases were AD. The risk of incident all-cause dementia increased log linearly with the severity of baseline hearing loss (1.27 per 10-dB loss; 95% confidence interval, 1.06-1.50). Compared with normal hearing, the hazard ratio (95% confidence interval) for incident all-cause dementia was 1.89 (1.00-3.58) for mild hearing loss, 3.00 (1.43-6.30) for moderate hearing loss, and 4.94 (1.09-22.40) for severe hearing loss. The risk of incident AD also increased with baseline hearing loss (1.20 per 10 dB of hearing loss) but with a wider confidence interval (0.94-1.53).

CONCLUSIONS

Hearing loss is independently associated with incident all-cause dementia. Whether hearing loss is a marker for early-stage dementia or is actually a modifiable risk factor for dementia deserves further study.

Distribution of PSA velocity by total PSA levels: data from the Baltimore Longitudinal Study of Aging

OBJECTIVES

To describe the distribution and implications of prostate-specific antigen velocity (PSAV) by prostate-specific antigen (PSA) in an unselected population. A PSAV >0.35 and >2.0 ng/mL/y have been associated with an increased risk of prostate cancer (CaP) death more than 10 years and 1 year before diagnosis, respectively. It is unknown how frequently PSAVs of this magnitude occur in community men.

METHODS

From the Baltimore Longitudinal Study of Aging, we examined the PSAV distribution in 786 men with serial PSA measurements (3474 PSAV observations) at total PSA levels <10 ng/mL. We also determined whether PSAV altered the probability of overall and life-threatening CaP at PSA levels <3 and 3-10 ng/mL.

RESULTS

Overall, the mean PSA and PSAV were 1.3 ng/mL and 0.05 ng/mL/y, respectively. PSAV rose continuously with increasing PSA (P <.0001), and was significantly higher in cancers than controls for observations at PSA levels <3 ng/mL (P = .02) and 3-10 ng/mL (P = .0008). The probability of life-threatening CaP was 3% at a PSA <3 ng/mL, but increased to 13.6% with PSAV >0.4 ng/mL/y. At PSA levels of 3-10 ng/mL, the probability of life-threatening CaP was 9.8% based on PSA alone vs 12% with PSAV >0.4 ng/mL/y.

CONCLUSIONS

PSAV was significantly higher in CaP observations than controls in all PSA ranges studied and altered the risk of overall and life-threatening CaP at a given PSA level. Because the value of PSAV is PSA-dependent, the PSA level should be taken into account when interpreting PSAV.