Validity of activity monitors in health and chronic disease: a systematic review.

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.

Treatment patterns, outcomes and costs among elderly patients with chronic myeloid leukaemia: a population-based analysis.

BACKGROUND AND OBJECTIVE: Chronic myeloid leukaemia (CML) affects approximately 3000-5000 Americans each year, with the American Cancer Society expecting 4600 new cases in 2004. The incidence of CML increases with age; median age at diagnosis is 67 years. Long-term data on the economic burden associated with CML among the elderly are sparse. To fill this void, our study uses population-based data to evaluate longer-term treatment patterns, outcomes and costs among elderly Medicare beneficiaries following their diagnosis of CML. PATIENTS AND METHODS: This retrospective cohort analysis used linked data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and Medicare claims. Study cohorts included 567 patients aged > or = 65 years newly diagnosed with CML between 1991 and 1993 in a SEER registry and followed for 5 years or until death, whichever occurred first. In addition, 567 control patients without CML matched 1 : 1 by age and sex (average age 78 years, 52% male) were included. The costs of care were based on total Medicare payments (in constant 1998 dollars). Groups were generally similar in terms of nonmatched variables. RESULTS: Five years following diagnosis, 13% of CML patients were still alive versus 68% of the control patients (median survival: 14 months vs > 60 months, respectively). The average total Medicare payments were USD35,785 for CML patients versus USD21,161 for control subjects (monthly payments: USD1688 vs USD428, respectively; p < 0.001). Approximately 25% of CML patients underwent Medicare-covered cancer treatment (11% outpatient chemotherapy, 6% inpatient chemotherapy and 8% outpatient interferon-alpha therapy). Younger patients and those diagnosed in the later years were most likely to be treated. Costs for treated patients were higher, and they lived longer. CONCLUSION: Our findings suggest low treatment rates, and substantial excess mortality and costs associated with CML among the elderly. The recent introduction of imatinib has dramatically changed the treatment of CML, which is likely to cause important changes to the economic burden of CML. Our results can be used as a baseline for evaluating the impact of such new therapies as data from clinical trials become available. Further work is needed to characterise this disease and the complex factors that influence treatment decisions and associated health outcomes in elderly patients.