Mats Pihlsgård

Incidence of airflow limitation in subjects 65-100 years of age.

The true incidence of chronic obstructive pulmonary disease is largely unknown, because the few longitudinal studies performed have used diagnostic criteria no longer recommended by either the European Respiratory Society or the American Thoracic Society (ATS). We studied the incidence and significance of airflow limitation in a population-based geriatric sample using both an age-dependent predicted lower limit of normal (LLN) value and a fixed-ratio spirometric criterion. Out of 2025 subjects with acceptable spirometry at baseline, 984 subjects aged 65–100 years completed a 6-year follow-up visit. Smoking habits were registered at baseline. Exclusion criteria were non-acceptable spirometry performance according to ATS criteria and inability to communicate. Airflow limitation was defined both according to forced expiratory volume in 1 s (FEV1)/forced vital capacity ratio <0.7 and <LLN. The incidence of airflow limitation per 1000 person-years was 28.2 using a fixed ratio and 11.7 with LLN, corresponding to a 1.41-fold higher incidence rate using a fixed ratio. The incidence increased dramatically with age when using a fixed ratio, but less so when using LLN. In addition, a sex effect was observed with the LLN criterion. LLN airflow limitation was associated with increased 5-year mortality. Presence of fixed-ratio airflow limitation in individuals classified by LLN as non-obstructive was not associated with increased mortality. Female sex may be a risk factor for developing chronic obstructive pulmonary disease http://ow.ly/TdgEd

Loss Rate Asymptotics in a GI/G/1 Queue with Finite Buffer

ABSTRACT We consider the stationary loss rate ℓ K of a GI/G/ 1 queue with finite buffer of size K. Let X n = U n −T n , n ≥ 1 where U n is the service time, T n is the interarrival time and let ρ be the traffic intensity. We derive sharp asymptotics for the loss rate as K → ∞ in the cases (i): ρ > 1 , and (ii): ρ < 1 and X n non–lattice with light tails. We also look at another reflection, related to Morans dam model. As an example, we look at the PH/PH/ 1 case, where we show how to compute the asymptotic loss rate as well as the exact one and illustrate our results numerically.

Anthropometric reference data for elderly Swedes and its disease-related pattern

Background/Objectives:Anthropometric measurement is a noninvasive and cost-efficient method for nutritional assessment. The study aims to present age- and gender-specific anthropometric reference data for Swedish elderly in relation to common medical conditions, and also formulate prediction equations for such anthropometric measurements.Subjects/Methods:A cross-sectional study among random heterogeneous sample of 3360 subjects, aged 60–99 years, from a population study ‘Good Aging in Scania. Means (±s.d.) and percentiles for height, weight, waist-, hip-, arm-, calf circumferences, triceps- (TST) and subscapular skinfold thickness (SST), body mass index (BMI), waist-hip ratio (WHR) and arm muscle circumference (AMC) were presented. The values were estimated based on the prevalence of myocardial infarction (MI), cardiac failure (CHF), stroke, cognitive impairment, dementia and dependence in daily living activities (ADL). Linear regression analysis was used to formulate the prediction equations.Results:Mean BMI was 27.5±5.8 kg/m2 (men) and 27.2±8.1 kg/m2 (women). WHR was higher among men (Men: 0.98±0.3, women: 0.87±0.2), except at age 85+ (women: 0.91±0.6). TST was 6.7±0.4 mm higher among women. Men with MI had BMI: 28.6±4.8 kg/m2 and SST: 21±9.2 mm, whereas subjects with dementia had lower weight (by 9.5±2.9 kg) compared with the non-demented. ADL-dependent women had BMI= 29.0±3.9 kg/m2, TST=19.2±1.3 mm.Conclusion:New normative data on gender- and age-specific anthropometrics on the general elderly population are presented. Cardiovascular diseases are associated with subcutaneous and central adiposity opposed to fat loss with dementia. ADL dependence indicates inadequate physical activity. The prediction models could be used as possible indicators monitoring physical activity and adiposity among the general elderly population hence potential health indicators in health promotion.

Nonlinear association between pulse wave velocity and cognitive function: a population-based study.

Background: Arterial stiffness has been hypothesized to contribute to cognitive decline. However, previous studies have reported inconsistent results. The aim of this cross-sectional study was to investigate the association between carotid–femoral pulse wave velocity (cfPWV), a marker of arterial stiffness, and cognitive function. Methods: The study population comprised 2637 individuals from the population-based Malmö Diet and Cancer Study (mean age 72.1 years, 60.8% women). During the follow-up examinations between 2007 and 2012, cfPWV and results on the a quick test of cognitive speed (AQT) and Mini Mental State Examination (MMSE) cognitive tests were measured. Results: After adjustments for demographics and traditional cardiovascular risk factors, a linear association was found between cfPWV and AQT (B = 0.37; P = 0.039). On the basis of hypothesis that individuals with high cfPWV values have worse cognitive function than can be inferred from a linear association, cfPWV was dichotomized at the 90th percentile (the binary variable denoted cfPWV >13.8). When cfPWV >13.8 was added to the model, the linear association between continuous cfPWV and AQT disappeared (B = –0.08; P = 0.72), but cfPWV >13.8 was highly significant (B = 4.81; P = 0.004). In the adjusted model with MMSE as outcome variable, cfPWV >13.8 also reached a statistically significant effect. Conclusion: Arterial stiffness was inversely associated with cognitive function in a nonlinear fashion, with individuals in the top decentile of cfPWV explaining the association. Results from linear regressions should thus be interpreted with caution because, even when statistical significance is reached, they can be explained by pronounced nonlinearity.

High degree of BMI misclassification of malnutrition among Swedish elderly population: Age-adjusted height estimation using knee height and demispan

Background/Objectives:The degree of misclassification of obesity and undernutrition among elders owing to inaccurate height measurements is investigated using height predicted by knee height (KH) and demispan equations.Subjects/Methods:Cross-sectional investigation was done among a random heterogeneous sample from five municipalities in Southern Sweden from a general population study ‘Good Aging in Skåne’ (GÅS). The sample comprised two groups: group 1 (KH) including 2839 GÅS baseline participants aged 60–93 years with a valid KH measurement and group 2 (demispan) including 2871 GÅS follow-up examination participants (1573 baseline; 1298 new), aged 60–99 years, with a valid demispan measurement. Participation rate was 80%. Height, weight, KH and demispan were measured. KH and demispan equations were formulated using linear regression analysis among participants aged 60–64 years as reference. Body mass index (BMI) was calculated in kg/m2.Results:Undernutrition prevalences in men and women were 3.9 and 8.6% by KH, compared with 2.4 and 5.4% by standard BMI, and more pronounced for all women aged 85+ years (21% vs 11.3%). The corresponding value in women aged 85+ years by demispan was 16.5% vs 10% by standard BMI. Obesity prevalences in men and women were 17.5 and 14.6% by KH, compared with 19.0 and 20.03% by standard BMI. Values among women aged 85+ years were 3.7% vs 10.4% by KH and 6.5% vs 12.7% by demispan compared with the standard.Conclusions:There is an age-related misclassification of undernutrition and obesity attributed to inaccurate height estimation among the elderly. This could affect the management of patients at true risk. We therefore propose using KH- and demispan-based formulae to address this issue.

Combining Cystatin C and Creatinine Yields a Reliable Glomerular Filtration Rate Estimation in Older Adults in Contrast to β-Trace Protein and β2-Microglobulin

Background: The glomerular filtration rate (GFR) is the most important measure of kidney function and chronic kidney disease (CKD). This study aims to validate commonly used equations for estimated GFR (eGFR) based on creatinine (cr), cystatin C (cys), β-trace protein (BTP), and β2-microglobulin (B2M) in older adults. Method: We conducted a validation study with 126 participants aged between 72 and 98 with a mean measured GFR (mGFR) by iohexol clearance of 54 mL/min/1.73 m2. The eGFR equations (CKD-Epidemiology collaboration [CKD-EPI], Berlin Initiative Study [BIS], Full Age Spectrum [FAS], Modification of Diet in Renal Disease [MDRD]cr, Caucasian-Asian-Pediatric-Adult [CAPA]cys, Lund-Malmö Revised [LM-REV]cr, and MEAN-LM-CAPAcr-cys), were assessed in terms of bias (median difference: eGFR-mGFR), precision (interquartile range of the differences), and accuracy (P30: percentage of estimates ±30% of mGFR). The equations were compared to a benchmark equation: CKD-EPIcr-cys. Results: All cystatin C-based equations underestimated the GFR compared to mGFR, whereas bias was mixed for the equations based only on creatinine. Accuracy was the highest for CKD-EPIcr-cys (98%) and lowest for MDRD (82%). Below mGFR 45 mL/min/1.73 m2 only equations incorporating cystatin C reached P30 accuracy >90%. CKD-EPIcr-cys was not significantly more accurate than the other cystatin C-based equations. In contrast, CKD-EPIcr-cys was significantly more accurate than all creatinine-based equations except LM-REVcr. Conclusion: This study confirms that it is reasonable to use equations incorporating cystatin C and creatinine in older patients across a wide spectrum of GFR. However, the results call into question the use of creatinine alone below mGFR 45 mL/min/1.73 m2. B2M and BTP do not demonstrate additional value in eGFR determination in older adults.

Lévy Processes with Two-Sided Reflection

Let X be a Levy process and V the reflection at boundaries 0 and b > 0. A number of properties of V are studied, with particular emphasis on the behaviour at the upper boundary b. The process V can be represented as solution of a Skorokhod problem V (t) = V (0) + X(t) + L(t) − U(t) where L, U are the local times (regulators) at the lower and upper barrier. Explicit forms of V in terms of X are surveyed as well as more pragmatic approaches to the construction of V, and the stationary distribution π is characterised in terms of a two-barrier first passage problem. A key quantity in applications is the loss rate l b at b, defined as \(\mathbb{E}_{\pi }U(1)\). Various forms of l b and various derivations are presented, and the asymptotics as \(b \rightarrow \infty \) is exhibited in both the light-tailed and the heavy-tailed regime. The drift zero case \(\mathbb{E}X(1) = 0\) plays a particular role, with Brownian or stable functional limits being a key tool. Further topics include studies of the first hitting time of b, central limit theorems and large deviations results for U, and a number of explicit calculations for Levy processes where the jump part is compound Poisson with phase-type jumps.

Male sex and vascular risk factors affect cystatin C-derived renal function in older people without diabetes or overt vascular disease

Background/objectives: to explore the effect of ageing on renal function with cystatin C as the marker of glomerular filtration rate (GFR) in the general population without vascular disease or diabetes. Design: a cross-sectional analysis of a healthy subset from the Good Aging in Skåne-cohort study representative of the Swedish general population. Subjects: 1252 participants without vascular disease and diabetes (43.9% men) of whom 203 were over 80 years old were included from the original cohort of 2931. Methods: plasma cystatin C and plasma creatinine were used as markers for GFR. Estimated GFR (eGFR) was calculated with three chronic kidney disease epidemiology collaboration (CKD-EPI) formulas involving cystatin C, creatinine or both. Results: the median for plasma cystatin C was 0.93 mg/l (60–69 years old), 1.04 (70–79 years old) and 1.24 (80+ years old). The difference in mg/l between the 5th and 95th percentile was 0.46, 0.62 and 0.90 for these age groups. Male sex increased the age effect on plasma cystatin C levels with 0.004 mg/l/year (P = 0.03), adjusted for vascular risk factors. Smoking, lower HDL and higher diastolic blood pressure were associated with higher cystatin C levels. 54.7% (CKD-EPI creatinine) to 73.9% (CKD-EPI cystatin C) of the 80+ had an eGFR < 60 ml/min/1.73 m2. Conclusion: non-diabetics without overt vascular disease exhibit an age related but heterogeneous decline in renal function. The ageing effect is more pronounced in men. At least half of healthy 80+ years old could be expected to have at least CKD Stage 3 with eGFR < 60 ml/min/1.73 m2.

No independent association between pulse wave velocity and dementia: a population-based, prospective study

Objective: Carotid–femoral pulse wave velocity (CFPWV), a marker of aortic stiffness, has been associated with cognitive test results and markers of cerebral small vessel disease, but its association with dementia has not been studied in detail. Our aim was to assess the association of CFPWV with prevalent and incident dementia in a large population-based study. Methods: In total, CFPWV was measured in 3056 participants of the Malmö Diet and Cancer study 2007–2012 (age range 61–85 years). Individuals scoring below preset cut-offs on cognitive screening tests were thoroughly evaluated for prevalent dementia. Also, dementia diagnoses were retrieved from the Swedish National Patient Register up until 31 December 2014, and then validated through medical records and neuroimaging findings. Results: We identified 159 cases of dementia, of which 57 were classified as prevalent, and 102 as incident during a median follow-up of 4.6 years. In fully adjusted logistic regressions, CFPWV was not associated with prevalent all-cause dementia (odds ratio 0.95 per 1 m/s increase in CFPWV, 95% confidence interval 0.83–1.08), and it did not predict incident all-cause dementia (odds ratio 1.00, 95% confidence interval 0.91–1.09). Neither was CFPWV associated with subtypes of dementia (Alzheimers disease, vascular dementia, mixed dementia), although the number of cases in subgroups were low. Conclusion: No independent association was found between CFPWV and dementia. It remains a matter of debate why CFPWV repeatedly has been associated with cognitive test results and markers of cerebral small vessel disease, but not with dementia.

Abnormal ductus venosus pulsatility index in the absence of concurrent umbilical vein pulsations does not indicate worsening fetal condition

Recordings of blood flow velocity waveforms in the ductus venosus (DV) and umbilical vein (UV) are routinely used in order to predict fetal condition in high‐risk pregnancies. The aim of this study was to investigate the relationship between pathological blood flow in the two vessels and perinatal outcome.