Association of biochemical values with morbidity in the elderly: a population‐based Swedish study of persons aged 82 or more years

A practical laboratory index to predict institutionalization and mortality - an 18-year population-based follow-up study

Background

Previously, several indexes based on a large number of clinical and laboratory tests to predict mortality and frailty have been produced. However, there is still a need for an easily applicable screening tool for every-day clinical practice.

Methods

A prospective study with 10- and 18-year follow-ups. Fourteen common laboratory tests were combined to an index. Cox regression model was used to analyse the association of the laboratory index with institutionalization and mortality.

Results

The mean age of the participants (n = 1153) was 73.6 (SD 6.8, range 64.0–100.0) years. Altogether, 151 (14.8%) and 305 (29.9%) subjects were institutionalized and 422 (36.6%) and 806 (69.9%) subjects deceased during the 10- and 18-year follow-ups, respectively. Higher LI (laboratory index) scores predicted increased mortality. Mortality rates increased as LI scores increased both in unadjusted and in age- and gender-adjusted models during both follow-ups. The LI did not significantly predict institutionalization either during the 10- or 18-year follow-ups.

Conclusions

A practical index based on routine laboratory tests can be used to predict mortality among older people. An LI could be automatically counted from routine laboratory results and thus an easily applicable screening instrument in clinical settings.

Immune parameters associated with mortality in the elderly are context-dependent: lessons from Sweden, Holland and Belgium

The pioneering Swedish OCTO/NONA-Immune longitudinal studies led by Anders Wikby in Jönköping in the 1990s established a cluster of simple baseline immune parameters associated with excess mortality in 85 year-old non-institutionalized individuals over 2, 4 and 6-year follow-up. We dubbed this cluster the "Immune Risk Profile" (IRP) consisting of poor proliferative responses of peripheral blood mononuclear cells to T cell mitogens, accumulations of CD8+ CD28- T-cells resulting in an inverted CD4:8 ratio, decreased amounts of B-cells, and seropositivity for Cytomegalovirus (CMV). The concept of the IRP has since been applied by others to many different populations in different circumstances and at different ages, but in general without specifically establishing whether the same risk factors were relevant in the tested subjects. However, our own later studies showed that risk factors in aged populations from The Netherlands and Belgium were markedly different, indicating that the IRP cannot simply be transferred between populations. Moreover, there was a striking sex difference in the Belgian study, which was the only one large enough to include sufficient numbers of old men. The reasons for these marked differences between populations which one might have assumed a priori to be quite similar to one another are not clear, and many candidates can be speculated upon, but the important lesson is that there is a marked context-dependency of immune biomarkers of ageing, suggesting that IRPs cannot be assumed to be identical in different populations.

Allostatic load and health in the older population of England: a crossed-lagged analysis

OBJECTIVE

Allostatic load, a composite measure of accumulated physical wear and tear, has been proposed as an early sign of physiological dysregulation predictive of health problems, functional limitation, and disability. However, much previous research has been cross sectional and few studies consider repeated measures. We investigate the directionality of associations between allostatic load, self-rated health, and a measure of physical function (walking speed).

METHODS

The sample included men and women 60 and older who participated in Wave 2 (2004) and Wave 4 (2008) of the English Longitudinal Study of Ageing (n = 6132 in Wave 2). Allostatic load was measured with nine biomarkers using a multisystem summary approach. Self-rated health was measured using a global 5 point summary indicator. Time to walk 8 ft was used as a measure of function. We fitted and tested autoregressive cross-lagged models between the allostatic load measure, self-rated health, and walking speed in Waves 2 and 4. Models were adjusted for age, sex, educational level, and smoking status at Wave 2 and for time-varying indicators of marital status, wealth, physical activity, and social support.

RESULTS

Allostatic load predicted slower walking speed (standardized estimate = -0.08, 95% confidence interval [CI] = -0.10 to -0.05). Better self-rated health predicted faster walking speed (standardized estimate = 0.11, 95% CI = 0.08-0.13) as well as lower allostatic load (standardized estimate = -0.15, 95% CI = -0.22 to -0.09), whereas paths from allostatic load and walking speed to self-rated health were weaker (standardized estimates = -0.05 [95% CI = -0.07 to -0.02] and 0.06 [95% CI = 0.04-0.08]).

CONCLUSIONS

Allostatic load can be a useful risk indicator of subsequent poor health or function.

Factors associated with increased risk for dementia in individuals age 80 years or older with congestive heart failure

BACKGROUND AND RESEARCH OBJECTIVE

An increasing body of evidence shows that individuals diagnosed with congestive heart failure (CHF) are at a higher risk for dementia. However, the prevalence rate of dementia among persons with CHF in very old individuals has not been previously reported, and little is known about the comorbidities that place old persons with CHF at a higher risk for dementia. The aim of this study was to compare the prevalence of dementia in individuals 80 years or older who have CHF with that in individuals without CHF and to identify factors related to dementia in individuals diagnosed with CHF.

METHODS

A total of 702 participants from a Swedish population-based longitudinal study (Octogenerian Twin) were included. The group consisted of same-sex twin pairs, age 80 years or older, and 138 participants had CHF. Dementia was diagnosed according to criteria in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Generalized estimating equations including gender, age and educational level, waist circumference, diabetes, hypertension, smoking, depression, and blood values were used in a case-control analysis.

RESULTS

Individuals with CHF had a significantly higher prevalence of vascular dementia, 16% vs 6% (P < 0.001), and of all types of dementia, 40% vs 30% (P < 0.01), than those not diagnosed with CHF. The generalized estimating equation models showed that depression, hypertension, and/or increased levels of homocysteine were all associated with a higher risk for dementia in individuals with CHF. Diabetes was specifically associated with an increased risk for vascular dementia.

CONCLUSIONS

The prevalence of dementia was higher among individuals with CHF than in those without CHF. Diabetes, depression, and hypertension in patients with CHF require special attention from healthcare professionals because these conditions are associated with an elevated risk for dementia. Higher levels of homocysteine were also found to be a marker of dementia in patients with CHF. Further research is needed to identify the factors related to dementia in individuals 80 years or older diagnosed with CHF.

Comparing age-wise reference intervals for serum creatinine concentration in a "Reality check" of the recommended cut-off

An increase in the communication within the healthcare services, both nationally and internationally, has strengthened the need for harmonization of measurements and reference intervals in laboratory medicine. In the present report, the calculated reference interval for serum creatinine (sCr) levels of healthy normal individuals (n=1121) in different sex and age groups are compared with the established interval. The calculated reference interval for sCr level was 0.4-1.3 mg/dL and 0.6 to 1.3 mg/dL in the age groups of 21-40 and 41-60 years respectively. The difference between the mean sCr values in total males and total females (age range 21-60 years) was statistically significant (p<0.0001); When male and female subjects were analyzed age-group wise, the data showed a significant difference in mean sCr values (p<0.0001) in three age groups (21-30, 31-40 and 41-50 years) however, in older age group (51-60 years), the difference was non-significant (p=0.07). The reference ranges were 0.7-1.3 and 0.4-1.0 mg/dL for males and females respectively where the lower limit was 0.1-0.2 units less than that of standard limits. An increase in the mean value of sCr was observed particularly in females with an increase in age. Hence it is of interest to validate an age specific reference ranges for sCr in our population.

Reference limits of plasma and serum creatinine concentrations from intra-laboratory data bases of several German and Italian medical centres: Comparison between direct and indirect procedures

BACKGROUND

The current dogma of establishing intra-laboratory reference limits (RLs) and their periodical reviewing cannot be fulfilled by most laboratories due to the expenses involved. Thus, most laboratories adopt external sources for their RLs often neglecting the problems of transferability. Therefore, several attempts were undertaken to derive RLs from the large data pools stored in modern laboratory information systems. These attempts were further developed to a more sophisticated indirect procedure. The new model can be considered a combined approach because it pre-excludes some subjects by direct criteria. In the current study, the new concept was applied to estimate RLs for serum and plasma creatinine from several German and Italian laboratories.

METHODS

A smoothed kernel density function was estimated for the distribution of the total mixed data of the sample group (combined data of non-diseased and diseased subjects). It was assumed that the "central" part of the distribution of all data represents the non-diseased ("healthy") population. The central part was defined by truncation points using an optimisation method, and was used to estimate a Gaussian distribution of the values of presumably non-diseased subjects after Box-Cox transformation of the empirical data. This distribution was now considered as the distribution of the non-diseased subgroup. The percentiles of this parametrical distribution were calculated to obtain RLs.

RESULTS

RLs determined by the indirect combined decomposition technique led to similar RLs as the classical direct method. Furthermore, the RLs obtained from 14 laboratories in 2 different European regions reflected the well-known differences of various analytical procedures. Stratification for gender and age was necessary. With rising age, an increase of the upper RL and of the reference range was observed. Hospitalization appeared also to affect the RLs. The new approach led to RLs in an artificially mixed population of diseased and non-diseased subjects (selected by clinical criteria) which were identical to RLs determined by a direct method applied to the non-diseased subgroup.

CONCLUSIONS

The proposed strategy of combining exclusion criteria with a resolution technique led to plausible retrospective RLs from intra-laboratory data pools for creatinine. Differences between laboratories were mainly due to the well-known bias of the different analytical procedures.

Homocysteine measurements in geriatric patients

OBJECTIVE

Homocysteine measurements may be relevant in geriatric medicine as homocysteine has been identified as an independent risk factor for prevalent disorders such as occlusive arterial vascular disease, cognitive impairment and dementia. The aim of the present study was to study diagnostic correlates of plasma total homocysteine (tHcy) in geriatric in-patients.

MATERIAL AND METHODS

Blood samples for the analysis of tHcy and related factors like serum vitamin B12, serum folate, red blood cell folate and clinical data were collected from geriatric patients (n=114) in stable clinical condition.

RESULTS

Almost 40% of the patients had tHcy values above 20 micromol/L. tHcy correlated significantly with serum folate, serum vitamin B12, serum creatinine and congestive heart failure, but not with red blood cell folate, cerebrovascular disease, coronary heart disease or cognitive impairment.

CONCLUSIONS

Hyperhomocysteinaemia seems to be frequent in geriatric patients and might primarily be an indicator of low folate and high creatinine values.

Synergism between smoking and alcohol consumption with respect to serum gamma-glutamyltransferase

There is increasing evidence that serum levels of the liver enzyme gamma-glutamyltransferase (gamma-GT) are an important predictor of incidence and mortality of various diseases. Apart from alcohol consumption, body mass index and smoking have been found to be associated with serum levels, but little is known about potential interactions of these factors. The aim of this study was to assess the individual and joint impact of alcohol consumption and smoking on levels of gamma-GT, with particular attention to potential differences by sex. The study was based on data of 8465 subjects aged 50 to 74 years, obtained at baseline examination of the ESTHER study, a large population-based cohort study in Germany. Exposure-outcome relationships were assessed in women and men, adjusting for potential confounders by multiple regression. In both sexes, moderate to heavy alcohol consumption (100+ g/week) was associated with 1.7-fold increased odds of elevated gamma-GT (>50 IU/L) in reference to nonsmoking alcohol abstainers, whereas smoking by itself was unrelated to gamma-GT. However, when moderate to heavy alcohol consumption was present in combination with heavy smoking, the odds ratios (95% CI) increased to 2.9 (1.1-7.6) in women and to 3.8 (2.2-6.6) in men (test for interaction between alcohol consumption and smoking: P(females) = 0.12, P(males) = 0.0017).

CONCLUSION

Our results support the notion of a detrimental interaction between cigarette smoking and alcohol consumption as determinants of elevated serum gamma-GT, especially in men.

Vascular risk factors and dementia in the general population aged >85 years: prospective population-based study

The aim of this study was to evaluate the association between dementia and common vascular risk factors including blood pressure, blood lipids, homocysteine and diabetes mellitus in a population of very old people. This study is a 9-year follow-up prospective population-based study monitoring 339 non-demented subjects aged 85 years or over in the city of Vantaa, Southern Finland. During the follow-up, those individuals with diabetes mellitus at the baseline and new incident stroke had a higher probability for developing dementia. History of hypertension or higher level of education were associated with a lower probability of dementia. It seems that the contribution of vascular risk factors to the risk of dementia may be age-dependent and their role in the very old subjects may be mediated through their influence on cerebrovascular morbidity. Thus, prevention of stroke and diabetes mellitus may reduce the risk of cognitive decline in the very old.

Associations between serum insulin and homocysteine in a Swedish population-a potential link between the metabolic syndrome and hyperhomocysteinemia: the Skaraborg project

The objective of this study is to examine the association between serum levels of insulin and homocysteine (Hcy) in a population-based sample of Swedish men and women. Men and women (537 and 571, respectively) 40 years or older, who were randomly selected from the population in Skara, southwestern Sweden, with valid information on serum levels of Hcy and insulin, were subject to a physical examination, including anthropometric measurement. Lifestyle factors were assessed by a questionnaire, and venous blood samples were drawn after an overnight fast. Insulin resistance was estimated by the homeostasis model assessment index. Homocysteine was higher in men (11.0 micromol/L) than in women (9.7 micromol/L) (P < .001) and was positively associated with age (P < .001 in both sexes) and serum creatinine (P = .009 in men, P < .001 in women), but inversely associated with leisure time physical activity (P = .012 in men, P = .001 in women). There was a positive association between serum insulin and serum Hcy independent of age and sex (P = .004). Upon exclusion of patients with diabetes and individuals with serum creatinine level greater than 130 microcat/L, this association was significant in the remaining 999 individuals also after adjustment for age, sex, serum creatinine, leisure time physical activity, body mass index, and smoking status (P = .003). A 1 SD difference in serum insulin corresponded to a difference of 0.5 micromol/L in serum Hcy. A similar association was found between insulin resistance and serum Hcy. In conclusion, there is an association between serum insulin and Hcy that may constitute a link between the metabolic syndrome and Hcy, either unilaterally or as part of a vicious circle.

Cobalamin: a critical vitamin in the elderly

Vitamin B(12) deficiency is a common problem in elderly subjects. If a serum cobalamin level of about 150 pmol/L (200 pg/mL) is considered normal, 10-15% of the elderly are deficient. Today, however, a threshold of 220-258 pmol/L (300-350 pg/mL) is recognized as desirable in the elderly, or else sensitive markers like the blood concentration of homocysteine or methylmalonic acid (MMA) are used. Then the prevalence of cobalamin deficiency rises to up to 43%. In the elderly, this high prevalence of poor cobalamin status is predominantly caused by atrophic gastritis type B. Atrophic gastritis results in declining gastric acid and pepsinogen secretion, and hence decreasing intestinal absorption of the cobalamin protein complexes from food. About 20-50% of the elderly are affected. Furthermore, the reduced acid secretion leads to an alkalinization of the small intestine, which may result in bacterial overgrowth and thus to a further decrease of the bioavailability of the vitamin. In addition, some drugs such as proton pump inhibitors or H2 receptor antagonists inhibit the intestinal absorption of vitamin B(12). An already moderately reduced vitamin B(12) level is associated with vascular disease and neurocognitive disorders such as depression and impaired cognitive performance. Furthermore, a poor vitamin B(12) status is assumed to be involved in the development and progression of dementia (e.g., Alzheimer's dementia). This is especially observable if the folic acid status is reduced as well. Due to the insecure supply, the cobalamin status of elderly persons (>/=60 years) should be regularly controlled and a general supplementation with vitamin B(12) (>50 microg/day) should be considered.