Alastair Glendenning

The assessment of physical activity in healthy populations and in those with chronic diseases is challenging. The aim of this systematic review was to identify whether available activity monitors (AM) have been appropriately validated for use in assessing physical activity in these groups. Following a systematic literature search we found 134 papers meeting the inclusion criteria; 40 conducted in a field setting (validation against doubly labelled water), 86 in a laboratory setting (validation against a metabolic cart, metabolic chamber) and 8 in a field and laboratory setting. Correlation coefficients between AM outcomes and energy expenditure (EE) by the criterion method (doubly labelled water and metabolic cart/chamber) and percentage mean differences between EE estimation from the monitor and EE measurement by the criterion method were extracted. Random-effects meta-analyses were performed to pool the results across studies where possible. Types of devices were compared using meta-regression analyses. Most validation studies had been performed in healthy adults (n=118), with few carried out in patients with chronic diseases (n=16). For total EE, correlation coefficients were statistically significantly lower in uniaxial compared to multisensor devices. For active EE, correlations were slightly but not significantly lower in uniaxial compared to triaxial and multisensor devices. Uniaxial devices tended to underestimate TEE (-12.07 (95%CI; -18.28 to -5.85) %) compared to triaxial (-6.85 (95%CI; -18.20 to 4.49) %, p=0.37) and were statistically significantly less accurate than multisensor devices (-3.64 (95%CI; -8.97 to 1.70) %, p<0.001). TEE was underestimated during slow walking speeds in 69% of the lab validation studies compared to 37%, 30% and 37% of the studies during intermediate, fast walking speed and running, respectively. The high level of heterogeneity in the validation studies is only partly explained by the type of activity monitor and the activity monitor outcome. Triaxial and multisensor devices tend to be more valid monitors. Since activity monitors are less accurate at slow walking speeds and information about validated activity monitors in chronic disease populations is lacking, proper validation studies in these populations are needed prior to their inclusion in clinical trials.

Abstract Background: The barriers to adherence with chelation therapy for chronically transfused and iron overloaded patients with sickle cell disease (SCD) have been described only anecdotally. Objectives: To describe barriers to home deferoxamine (DFO) administration adherence among adults with SCD. It was hypothesized that barriers would include limited patient education on the importance of chelation and perceived aversiveness of the regimen. Methods: Medical records were reviewed for 189 adult patients seen at a comprehensive sickle cell center. Patients with transfusion induced hemosiderosis, defined as a serum ferritin ≥ 1500 ng/ml, were administered a four item interview asking if iron overload had ever been discussed with them; if they had been informed they were iron over loaded; if chelation therapy had been offered; and if not currently home chelating, why not. Patients not interviewed were deceased (3); unavailable (10); or declined (3). A study coordinator who did not provide clinical care conducted the interviews. Results: 54 of the 189 patients (29%) had a history of intermittent or chronic transfusion, or pheresis. 45 of these patients were iron overloaded. 29 of these patients agreed to complete the interview; 22 (76%) were female. Average age was 41.5 years (range 22.4 – 58.4 years) and average serum ferritin was 4240.8 (range 1547 – 9420). 23 of the 29 patients (79%) reported that their physician or nurse had discussed iron overload and chelation with them. 16 of these (55%) reported that they were currently receiving home DFO therapy. Reasons given for not administering home DFO included: Reason Number (%) “Don’t want to stick self” 3 (23) No longer being transfused or being exchanged 3 (23) Awaiting clinical trial for oral chelator 2 (15) Home situation too complex 2 (15) Don’t want to (no further explanation) 2 (15) Too many adverse effects 1 (8) Discussion: Life threatening levels of iron overload were observed in intermittently transfused adult sickle cell patients. Contrary to expectations, iron overload and its treatment had been discussed with most patients. However, just over half were currently chelating at home. Toxicity of DFO and misunderstanding that iron overload is no longer a problem if chronic transfusion therapy stops are the most common reasons for non-compliance. Repeated patient counseling are essential in order to prevent progressive iron toxicity in sickle cell disease. Reason Number (%) “Don’t want to stick self” 3 (23) No longer being transfused or being exchanged 3 (23) Awaiting clinical trial for oral chelator 2 (15) Home situation too complex 2 (15) Don’t want to (no further explanation) 2 (15) Too many adverse effects 1 (8)