The Burden of Functional Disabilities for Middle-Aged and Older Adults in the United States

OBJECTIVES

Understanding the role of functional capacity on longevity is important as the population in the United States ages. The purpose of this study was to determine the burden of instrumental activities of daily living (IADL) and activities of daily living (ADL) disabilities for a nationally-representative sample of middle-aged and older adults in the United States.

DESIGN

Longitudinal-Panel.

SETTING

Core interviews were often performed in person or over the telephone.

PARTICIPANTS

A sub-sample of 31,055 participants aged at least 50 years from the 1998-2014 waves of the Health and Retirement Study who reported having a functional disability were included.

MEASUREMENTS

Ability to perform IADLs and ADLs were self-reported at each wave. The National Death Index was used to ascertain date of death. The number of years of life that were lost (YLLs) and years lived with a disability (YLDs) were summed for the calculation of disability-adjusted life years (DALYs). Sampling weights were used in the analyses to make the DALYs nationally-representative. The results for YLLs, YLDs, and DALYs are reported in thousands.

RESULTS

Of the participants included, 14,990 had an IADL disability and 13,136 had an ADL disability. Men and women with an IADL disability had 236,037 and 233,772 DALYs, respectively; whereas, there were 178,594 DALYs for males and 253,630 DALYs for females with an ADL disability. Collectively, there were 469,809 years of healthy life lost from IADL impairments, and 432,224 years of healthy life lost from ADL limitations.

CONCLUSIONS

These findings should be used to inform healthcare providers and guide interventions aiming to preserve the functional capacity of aging adults. Prioritizing health-related resources for mitigating the burden of functional disabilities may help aging adults increase their quality of life and life expectancy over time.

Determination of metabolic stability of positron emission tomography tracers by LC–MS/MS: An example in WAY-100635 and two analogues

A method is presented for determination of microsomal metabolic stability of potential positron emission tomography (PET) tracers by LC-MS/MS in the lower nm range. The PET tracers used for the study were the serotonin receptor antagonist WAY-100635 and two potential tracer analogues. The sensitivity permitted the substrates to be directly collected from PET radiolabelling batches, containing very low amounts of substance (0.3-7 microg), for subsequent metabolic stability incubations. Sample preparation was minimal, with addition of internal standard, acetonitrile and a fast centrifugation step, as a result of the low protein concentration of the microsome solutions. Linearity (R2 > or = 0.99), precision (inter-assay R.S.D. < 7%) and accuracy (bias < or = 8%) for the tested concentration range 0.5-5 nM proved to be well within accepted limits. No significant differences in metabolic rates were detected using substrates from cold (non-labelling) chemistry syntheses and PET labelling batches, indicating the validity of using substrates from the latter source. A para-methoxy-benzamide analogue (MeO-WAY) displayed a significantly lower rate of metabolism compared to WAY-100635, whereas a para-iodo-benzamide analogue was more susceptible to metabolic transformation. LC-MS/MS Analysis of formed metabolites from WAY-100635 and MeO-WAY suggested similar metabolic pathways, with hydroxylation, demethylation and dearylation reactions. The main metabolic route in humans, amide hydrolysis, was not observed with the rat liver microsome assay.

Determination of flumazenil in human plasma by liquid chromatography-electrospray ionisation tandem mass spectrometry

A liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to determine unlabelled flumazenil (Ro 15-1788) in human plasma in [11C]flumazenil positron emission tomography (PET) studies. N-Methyl tri-deuterated flumazenil was used as an internal standard. The analyte and internal standard were extracted from plasma samples using solid-phase extraction, with a recovery of 78%. This was determined through the convenience of radioactivity measurements of 11C-labelled flumazenil. The evaporated and reconstituted eluate was analysed by LC-ESI-MS/MS. The calibration curve was linear over the tested concentration range of 0.05-0.5 nM (15-150 pg/ml) with a correlation coefficient, R2, of 0.998+/-0.001. A high precision was achieved, with mean intra-assay and inter-assay relative standard deviations of at most 6 and 7%, respectively. The accuracy of the method ranged from 95 to 104%. As a proof of concept, the validated method was applied in the determination of flumazenil in plasma from two healthy volunteers participating in a PET study with three repeated investigations. A bolus-infusion protocol was used to achieve a constant concentration level of flumazenil. The average plasma concentrations ranged from 0.11 and 0.19 nM and all measurements were within the calibration standard range. The flumazenil concentrations were relatively constant within each scan and the average intra-scan precision was 15%.

Analysis of microsomal metabolic stability using high-flow-rate extraction coupled to capillary liquid chromatography–mass spectrometry

A method is described for on-line high-speed extraction of microsomal samples and analysis by capillary liquid chromatography-mass spectrometry (LC-MS) for the determination of metabolic stability in connection with the development of positron emission tomography (PET) tracers. The method allowed direct injections of large sample volumes at a fast extraction rate, providing a gain in both sensitivity and sample preparation time. The calibration curve of the test compound flumazenil (Ro 15-1788) was linear in the concentration range of 1-150 nM, with a correlation coefficient exceeding 0.999. The accuracy of the method ranged from 98 to 101%. A high precision was obtained, with mean intra-assay and inter-assay relative standard deviations of at most 1.4 and 1.5%, respectively, for quality control (QC) samples. The extraction efficiency was determined to be 99.4%, the total recovery 96% and the carryover to <or=0.23%. Extractions were performed in a concentration interval of 30-3000 nM without any sign of column overload. The method was successfully used for determining the microsomal metabolic stability of flumazenil. As a result, the described analysis system is currently used for metabolic screening of PET tracer candidates in our laboratory.

Enhanced microdialysis of neuropeptides

An enhanced microdialysis method for neuropeptides is described and some preliminary results of this novel approach are presented. The enhancement is achieved by adding a vehicle (solid support) to the perfusion fluid in order to increase the diffusion coefficient across the membrane and efficiently transport the analytes towards the detector. The microdialysis samples are desalted and then analyzed on an electrospray ionization orthogonal time-of-flight mass spectrometer. The preliminary results show major increase in signal when comparing this new approach of microdialysis with ordinary microdialysis.

Enhanced microdialysis of neuropeptides

An enhanced microdialysis method for neuropeptides is described and some preliminary results of this novel approach are presented. The enhancement is achieved by adding a vehicle (solid support) to the perfusion fluid in order to increase the diffusion coefficient across the membrane and efficiently transport the analytes towards the detector. The microdialysis samples are desalted and then analyzed on an electrospray ionization orthogonal time-of-flight mass spectrometer. The preliminary results show major increase in signal when comparing this new approach of microdialysis with ordinary microdialysis.

Effect of sequence length, sequence frequency, and data acquisition rate on the performance of a Hadamard transform time-of-flight mass spectrometer

Various factors influencing the performance of a Hadamard transform time-of-flight mass spectrometer (HT-TOFMS) have been investigated. Using a nitrogen corona discharge to produce an ion stream of N2+, N3+, and N4+, it is found for spectra containing only N4+ that the signal-to-noise ratio (SNR) closely approaches the value calculated from the ion background by assuming that the ion background follows a Poisson distribution. In contrast, for a more intense beam containing N2+, N3+, and N4+, the SNR is less than its theoretical value because of the appearance of discrete spikes in the mass spectrum caused by deviations in the actual modulation sequence from the ideal one. These spikes can be reduced, however, by decreasing the modulation voltage. Under these optimized conditions, the pseudo-random sequence length is varied to understand how it alters SNR, mass resolution, and scan speed. When the length of the pseudo-random sequence is doubled, the SNR increases by the square root of 2 while the time necessary to record a mass spectrum also doubles. Mass resolution can be varied between 500 and 1200 at m/z = 609 as the sequence length, modulation speed (10 MHz, 25 MHz), and acquisition rate (up to 50 MHz) are changed. Scan speeds of 6000 passes per s can be obtained using a sequence containing 4095 elements modulated at 25 MHz. The capability to tailor the HT-TOFMS to increase the scan speed and resolution with a constant 50% duty cycle makes the technique extremely appealing as a mass analyzer for measuring rapid changes in the composition of an ion stream.

Evaluations of the stability of sheathless electrospray ionization mass spectrometry emitters using electrochemical techniques

The processes that cause the failure of sheathless electrospray ionization (ESI) emitters, based on different kinds of gold coatings on fused-silica capillaries, are described and explained. The methods chosen for this study include electrochemical methods, ICPMS analysis of the electrolytes used, SEM studies, and electrospray experiments. Generally, the failure occurs by loss of the conductive coating. It is shown that emitters with sputter-coated gold lose their coatings because of mechanical stress caused by the gas evolution accompanying water oxidation or reduction. Emitters with gold coatings on top of adhesion layers of chromium and nickel alloy withstand this mechanical stress and have excellent durability when operating as cathodes. When operating as anodes, the adhesion layer is electrochemically dissolved through the gold film, and the gold film then flakes off. It is shown that the conductive coating behaves as a cathode even in the positive electrospray mode when the magnitude of a superimposed reductive electrophoretic current exceeds that of the oxidative electrospray current. Fairy-dust coatings developed in our laboratory (see Barnidge, D. R.; etal.Anal. Chem. 1999, 71, 4115-4118,) bygluing gold dust onto the emitter, are unaffected by the mechanical stress due to gas evolution. When oxidized, the fairy-dust coatings show an increased surface roughness and decreased conductivities due to the formation of gold oxide. The resistance of this oxide layer is however negligible in comparison with that of the gas phase in ESI. Furthermore, since no flaking and only negligible electrochemical etching of gold was found, practically unlimited emitter lifetimes may be achieved with fairy-dust coatings.

Optimization of capillary electrophoresis conditions for coupling to a mass spectrometer via a sheathless interface

When optimizing a capillary electrophoresis/electrospray ionization mass spectrometry (CE/ESI-MS) system, consideration has to be given not only to the separation but also to the electrospray stability. Methods developed for CE/UV analysis of drugs and peptides were considered and modified to be suitable for a CE/MS system with a robust sheathless interface. Different concentrations of the organic modifiers acetonitrile, methanol and 2-propanol were used in the separation buffer. The type and concentrations of these modifiers were also compared with reference to electrospray stability, sensitivity and time of analysis. In addition, different ionic strengths in the buffers were evaluated with reference to electrospray stability. The repeatability was used for the estimation of electrospray stability. The degree to which these parameters influenced the separation and the ESI stability was studied using a nine-peptide standard mixture and the antibiotic drugs bacampicillin and ampicillin as test substances. The analysis time and resolution were used as measures of the efficiency of the separation. A time-of-flight MS analyzer was used since it has the potential advantages of becoming a better fit for integration of CE with MS owing to the speed and sensitivity of this mass analyzer. The detection limit, i.e. 1 microM, for bacampicillin was comparable to what could be achieved with CE/MS on a quadrupole instrument using selected ion monitoring and sheath flow ESI.

Current awareness

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (5 Weeks journals - Search completed at 27th. Apr 2000)

Analysis of enzymatically digested proteins and protein mixtures using a 9.4 Tesla Fourier transform ion cyclotron mass spectrometer

A commercially available 9.4 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was applied in the analysis of tryptic digests of protein mixtures without any separation. First, the method was demonstrated on a mixture of tryptic digests of equine cytochrome c, equine myoglobin and bovine serum albumin. The same method was then applied to human plasma from a healthy blood donor. Computer programs were employed to simplify analysis of the complex spectra. The 2745 peaks in the human plasma electrospray ionization FTICR spectrum could be reduced to 1165 isotopic clusters and 669 unique masses. Out of these, 82 masses matched tryptic fragments of serum albumin with mass measurement errors less than 10 ppm, covering 93% of the sequence. Another 16 masses were assigned to tryptic fragments of transferrin, covering 41% of the sequence on the 10 ppm mass measurement error level (14 within 2 ppm). The mass measurement errors were approximately normal distributed with a standard deviation of 1.7 ppm. This demonstrates the feasibility of combining the ultra-high mass resolving power and accuracy of FTICR mass spectrometry with automated computer analysis for investigating complex biological matrices.

Compounds labelled with short-lived beta(+)-emitting radionuclides and some applications in life sciences. The importance of time as a parameter

Some examples of recent development of the synthesis of compounds labelled with short-lived beta(+)-emitting radionuclides will be discussed with an emphasis on the importance of time in selecting a synthetic strategy. Furthermore the use of such labelled compounds to monitor certain processes in areas within the field of analytical chemistry and in various applications in drug development will be presented.

Tri-ethnic alcohol use and religion, family, and gender

Nine different behavioral responses to alcohol by over two hundred ninth-graders in Austin, Texas, were examined in a survey designed to identify the relationship between adolescents' alcohol use, religious affiliation, religiosity, and gender. The relationship between alcohol use and family adaptability was also examined. While religious affiliation was found to be mildly predictive of use, religiosity determined only specific behavior. Gender differences in alcohol use appeared to be narrowing. Family adaptability was the most predictive variable, showing a relationship with six of the nine kinds of alcohol behavior. Future studies of family influences on adolescents' alcohol behavior and alcohol use among females are recommended.

Measuring social support among older adults

The purpose of this study is to introduce a measure of natural supportive behaviors for use in studies that examine the relationship between stress, social support, and health among older adults. The index improves on existing measures in three ways: it avoids problems arising from confounding potentially supportive relationships with support that is actually received; the scale also assesses variations in individual support needs; and it measures four distinct dimensions of social support (informational support, tangible help, emotional support, and integration). Based on data from a random community survey of 351 older adults, the basic psychometric properties and the factor structure of the scale are explored. The predictive validity of the scale is demonstrated by showing that the dimensions of support buffer the stressful effects of bereavement on depressive symptoms.

Illness of spouse and psychological well-being in older adults

The purpose of this study is to determine whether illness of a spouse is a source of significant psychological distress for older adults. In addition, we also examine whether two intervening variables (chronic financial strain and chronic marital strain) might explain why this relationship exists. A final goal of this study was to determine whether gender differences exist in the relationships among these indicators. Findings from a random community survey of elderly people suggest that while illness of spouse exerts significant direct effects on depression for both older men and older women, the indirect effects through financial and martial strain are largely restricted to elderly women.