Long-term Rate Of Decline Research Articles

Monitoring 6-month trajectory of grip strength improves the prediction of long-term change in grip strength in disabled older women.

This study aims to assess the degree and heterogeneity of decline in grip strength in the short term (6 months) and the clinical relevance of short-term decline to long-term decline (2.5 years) in grip strength in disabled older women. Eighty-four community-dwelling disabled women aged 65 years or older were evaluated on a weekly basis over 6 months, followed by an additional five semi-annual visits for a total follow-up of 3 years. The study outcome is maximum isometric handgrip strength in the nondominant hand. Linear random effects models were used to characterize population- as well as individual-level change in grip strength over time. In the weekly assessments over the initial 6 months, individual-level short-term change in grip strength was detectable (mean = -0.12 kg/month; p = .06), heterogeneous (range: -2.03 ± 0.95 kg/month), and independent of absolute grip strength at baseline (mean = 18.4 kg). Additionally, among women with grip strength greater than 16.7 kg at baseline, the long-term rate of decline in grip strength was accelerated by 0.15 kg/year (p = .014) for every 0.5 standard deviation (0.25 kg/month) increase in the short-term rate of decline. The baseline absolute grip strength, however, was not significantly associated with the long-term rate of decline (correlation = -0.36, p = .105). Our findings suggest that short-term change in grip strength is detectable and meaningful for disabled older women and it is the individual's past trajectory of grip strength relative to her current strength level, not her current absolute strength per se, that is important for predicting future strength decline.

The reversibility of CO2 induced climate change

This paper investigates the reversibility of CO2 induced climate change and in particular the potential impacts of different rates of CO2 reduction using a coupled climate model. Atmospheric CO2 concentration is ramped up by 0.5 %/year from the preindustrial value to 4×CO2 and then ramped down from 2×CO2 to 4×CO2 with different rates. How the response of the climate system is affected by the peak atmospheric CO2 concentration and the rate of long term decline is vital information for those considering hypothetical geoengineering options to remove CO2. Major components of the climate system including global mean surface air temperature and precipitation, contribution of thermal expansion to global sea level rise, loss of the Arctic sea ice, weakening of the Atlantic meridional overturning circulation (AMOC) and the South Asia monsoon are analyzed. We have found no ‘tipping points’ or thresholds beyond which CO2 induced climate change in these components become irreversible within this model under the specific scenarios. However, there are strong inertias and path-dependent hysteresis in the climate system linked through oceanic memory. Initially the strengthened global hydrological cycle accelerates further in response to a CO2 ramp-down before weakening. Thermal expansion of the oceans continues for many decades after CO2 concentration starts to decrease. A 0.5 %/year reduction from 4×CO2 could see a further 25 % sea level rise. The weakening of the AMOC is reversible, but the build-up of highly saline subtropical waters during global warming drives an overshoot of the AMOC after the CO2 ramp-down and extends the warming of the northern high latitudes by many decades. The South Asia monsoon strengthens in response to a CO2 ramp-up marked by an increase in summer monsoon rainfall. This increase reverses rapidly following a CO2 ramp-down, displaying an undershoot in monsoon rainfall for rapid CO2 reductions.

Resolving the Enigma of Infant Mortality Rate in Colombia

The infant mortality rate (IMR) in Colombia has been subject to considerable inconsistent reporting, estimation, and debate. The registered rate for 2009 is 13.69, while the estimated rate by Colombia’s Departamento Nacional de Estadistica (DANE) is 20.13. These rates combined with different measurements and estimates of long-term decline, ranging from 2.5 to 7.5 percent, yield even wider discrepancies in IMR for previous years. Taking advantage of all relevant data that have become available -- including 443,338 deaths (1979-2009) and 8,636,510 birth records (1998-2009) -- we establish the most probable range of IMR in Colombia since 1980, including the period 1988 through 1997 for which data on births is lacking. Using the general relationship IMR=αeβt -- where α is the projected initial level of IMR, and β is the average long term rate of annual decline -- we derive α and β from related estimates of infant deaths and birth per 10,000 women age 15-49. Initial estimates set the boundaries for plausible IMR in Colombia for the period based on the registered, 13.69 and estimated, 20.13, rates for 2009, and long term average rates of decline in IMR between 3.8 and 7.6 percent. A further analysis based on other sources, recent developments in vital registration in Colombia, and relevant international experience, lead to a considerable narrower band of most probable IMR for Colombia based on a the range in IMR between 15.5 to 17.5 IMR in 2009 and average long term rates of decline between 4.0 and 6.0 percent, the lower estimates more likely.

Rate of FEV1 Change Following Lung Volume Reduction Surgery

Lung volume reduction surgery (LVRS) improves pulmonary function and dyspnea symptoms acutely in selected patients with heterogeneous emphysema. Limited data are available regarding long-term function following LVRS. We analyzed short-term (<6 months) and long-term rate of change of pulmonary function in 376 patients who underwent unilateral or bilateral LVRS using thoracoscopic or median sternotomy, staple, laser, or combined techniques. We hypothesized that the long-term rate of deterioration in lung function would be dependent on the surgical procedure used and would be greatest in those with the largest short-term postoperative improvement. Pulmonary function was assessed preoperatively and at repeated intervals following LVRS. The change in pulmonary function over time was assessed for each patient by determining the individual change in FEV1 using linear regression analysis short and long term. Overall rate of change in pulmonary function was calculated for the composite group of patients and subgrouped by operative procedure. Lung function appears to improve in the first few months following LVRS in most patients, maximizing at approximately 3 to 6 months and declining thereafter. The short-term incremental improvement following staple procedures is superior to improvements following laser procedures or unilateral surgery: FEV1 increase (mean+/-SD) of 0.39+/-0.03 L for bilateral staple, 0.25+/-0.03 L for unilateral staple, 0.10+/-0.03 L for unilateral laser, and 0.22+/-0.1 L for mixed unilateral staple/laser procedures. However, the long-term rate of decline in FEV1 was greatest for bilateral staple LVRS procedures as well: 0.255+/-0.057 L/yr for bilateral staple, 0.107+/-0.068 L/yr for unilateral staple, 0.074+/-0.034 L/yr for unilateral laser, and 0.209+/-0.12 L/yr for mixed staple laser procedures. There was a general correlation between the magnitude of short-term incremental improvement and the rate of deterioration in FEV1 (r=0.292, p=0.003). While bilateral staple LVRS procedures lead to greater short-term improvement in FEV1, the more rapid rate of FEV1 decline in these patients and the general association between greater short-term incremental improvement and higher rates of deterioration raise questions regarding optimal long-term procedures. Further studies will be needed to answer these important questions.

Self-Perception Theory, Salience of Behavior, and a Control-Enhancing Program for the Elderly

Accessibility of attitudes was manipulated (frequent reminders through active experience based on the subjects' own behavior) for geriatric nursing home residents in an enhanced visitor control program. Thirty sublets (mean age 82.6 years) were randomly assigned to one of three groups: a high- or low-behavior-salience condition or a no-treatment condition. Subjects completed Forms A and B of the Life Satisfaction Index 1 week prior to, and 1 week after, the program. A nurse administrator additionally rated each subject on Health Status and Zest for Life scales at these times and at 1-month and 12-month follow-up times. Results showed that in comparison to the no-treatment group, both visitor control programs helped the residents, and that the high-salience condition was most helpful. Furthermore, this condition was associated with a slower rate of long-term decline. Results are interpreted as being consistent with Bern's (1972) self-perception theory.