Utility of total lymphocyte count as a surrogate marker for CD4 counts in HIV-1 infected children in Kenya

<p>Abstract</p> <p>Background</p> <p>In resource-limited settings, such as Kenya, access to CD4 testing is limited. Therefore, evaluation of less expensive laboratory diagnostics is urgently needed to diagnose immuno-suppression in children.</p> <p>Objectives</p> <p>To evaluate utility of total lymphocyte count (TLC) as surrogate marker for CD4 count in HIV-infected children.</p> <p>Methods</p> <p>This was a hospital based retrospective study conducted in three HIV clinics in Kisumu and Nairobi in Kenya. TLC, CD4 count and CD4 percent data were abstracted from hospital records of 487 antiretroviral-naïve HIV-infected children aged 1 month - 12 years.</p> <p>Results</p> <p>TLC and CD4 count were positively correlated (r = 0.66, p < 0.001) with highest correlation seen in children with severe immuno-suppression (r = 0.72, p < 0.001) and children >59 months of age (r = 0.68, p < 0.001). Children were considered to have severe immuno-suppression if they met the following WHO set CD4 count thresholds: age below 12 months (CD4 counts < 1500 cells/mm³), age 12-35 months (CD4 count < 750 cells/mm3), age 36-59 months (CD4 count < 350 cells/mm³, and age above 59 months (CD4 count < 200 cells/mm³). WHO recommended TLC threshold values for severe immuno-suppression of 4000, 3000, 2500 and 2000 cells/mm³for age categories <12, 12-35, 36-59 and >59 months had low sensitivity of 25%, 23%, 33% and 62% respectively in predicting severe immuno-suppression using CD4 count as gold standard. Raising TLC thresholds to 7000, 6000, 4500 and 3000 cells/mm³for each of the stated age categories increased sensitivity to 71%, 64%, 56% and 86%, with positive predictive values of 85%, 61%, 37%, 68% respectively but reduced specificity to 73%, 62%, 54% and 68% with negative predictive values of 54%, 65%, 71% and 87% respectively.</p> <p>Conclusion</p> <p>TLC is positively correlated with absolute CD4 count in children but current WHO age-specific thresholds had low sensitivity to identify severely immunosuppressed Kenyan children. Sensitivity and therefore utility of TLC to identify immuno-suppressed children may be improved by raising the TLC cut off levels across the various age categories.</p

Coupling of lower and upper extremity forces during walking with assistive devices in community-dwelling older adults.

Coupling of lower and upper extremity forces during walking with assistive devices in community-dwelling older adults. Alpert, D.A., Barklund, K.B., Buchanan, C., Roberts, D.B., Spitalnic, K.L., Peters, D.M. Department of Rehabilitation and Movement Science Doctor of Physical Therapy Program, The University of Vermont ABSTRACT Background & Objectives: This study was conducted to establish reliable methodology to examine the coupling between upper extremity (UE) and lower extremity (LE) force production in older adults who use an assistive device (AD) for walking. ADs are commonly used in the community-dwelling population to aid in mobility, balance, propulsion, and speed; however, ADs may limit the ability to produce forces through the LEs. Additionally, AD use may result in excessive amounts of force placed through the UE(s) during gait, which can lead to potential overuse injuries. Currently, there are no studies that have examined the coupling of UE and LE forces during gait. Results from our study may provide insight regarding force production with AD-assisted gait, contributing to a better understanding of the strategies utilized by the older adult population during walking with an AD. Methods: Data will be collected from individuals between the ages of 60-85 years of age who regularly use an AD with walking, and who have no significant weight-bearing pain or previous neurological conditions. Participants will complete clinical measures of walking ability and strength, and will walk across an walkway with embedded force plates while using an instrumented AD (cane or walker) reflective of their typical AD. Multiple walking trials will be performed in order to capture a minimum of 3-5 trials of combined UE/LE force production for both self-selected (SSWS) and fast walking speed (FWS) conditions. The order of walking speed conditions (SSWS, FWS) will be randomized between subjects to minimize order and fatigue effects. Normality of data will be assessed using the Shapiro-Wilk test. Test-retest reliability of UE/LE force production measures across walking trials will be assessed using intra-class correlation coefficient (ICC). Correlational analyses will be used to examine relationships between measures of force production and clinical measures of LE strength and walking speed. Correlations between muscle activity (EMG) and force production will also be assessed. Results: Data collection and analyses are currently ongoing