Validation of Proprietary and Novel Step-counting Algorithms for Individuals Ambulating With a Lower Limb Prosthesis

OBJECTIVE

To compare the accuracy and reliability of 10 different accelerometer-based step-counting algorithms for individuals with lower limb loss, accounting for different clinical characteristics and real-world activities.

DESIGN

Cross-sectional study.

SETTING

General community setting (ie, institutional research laboratory and community free-living).

PARTICIPANTS

Forty-eight individuals with a lower limb amputation (N=48) wore an ActiGraph (AG) wGT3x-BT accelerometer proximal to the foot of their prosthetic limb during labeled indoor/outdoor activities and community free-living.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Intraclass correlation coefficient (ICC), absolute and root mean square error (RMSE), and Bland Altman plots were used to compare true (manual) step counts to estimated step counts from the proprietary AG Default algorithm and low frequency extension filter, as well as from 8 novel algorithms based on continuous wavelet transforms, fast Fourier transforms (FFTs), and peak detection.

RESULTS

All algorithms had excellent agreement with manual step counts (ICC>0.9). The AG Default and FFT algorithms had the highest overall error (RMSE=17.81 and 19.91 steps, respectively), widest limits of agreement, and highest error during outdoor and ramp ambulation. The AG Default algorithm also had among the highest error during indoor ambulation and stairs, while a FFT algorithm had the highest error during stationary tasks. Peak detection algorithms, especially those using pre-set parameters with a trial-specific component, had among the lowest error across all activities (RMSE=4.07-8.99 steps).

CONCLUSIONS

Because of its simplicity and accuracy across activities and clinical characteristics, we recommend the peak detection algorithm with set parameters to count steps using a prosthetic-worn AG among individuals with lower limb loss for clinical and research applications.

Design refinement and evaluation of a mobile manual standing wheelchair

PURPOSE

There are no manually propelled wheelchairs on the market that are mobile in both seated and standing positions. In response to this product gap, our group formerly designed a mobile manual standing wheelchair (MMSW) and gathered stakeholder feedback. The purpose of this study was to refine the MMSW based on feedback, including weight and width reduction, and evaluate its performance.

MATERIALS AND METHODS

The MMSW was subjected to ANSI/RESNA stability testing, and three male participants completed a subset of the wheelchair skills test, including a 100-m roll test in the MMSW (seated and standing) and in their ultralight wheelchair.

RESULTS

The MMSW met ANSI/RESNA stability safety standards. During the 100-m roll test, participants reached speeds with the MMSW in both the standing and sitting postures similar or greater than those typical of moving in the home environment (1.11 m/s seated; 0.79 m/s standing). Mobility speeds in the MMSW in the standing position were about three times faster than average walking speeds in exoskeletons (0.26 m/s exoskeletons). With the addition of chain drive bracing to the MMSW, one user was able to reach speeds in the standing position similar to average neurotypical walking speeds indicating the possibility for wheelchair users to be able to move in pace with family and friends.

CONCLUSION

All participants expressed interest in the MMSW to facilitate improved quality of life. Further work is needed to test the utility of the MMSW in home and community settings, and its potential effects on standing time and health outcomes.Implications for rehabilitationManual standing wheelchairs with standing mobility may increase functional utility and length of standing time for manual wheelchair usersIncreased standing time may lead to several health benefits for manual wheelchair users.

Elimination of human onchocerciasis: history of progress and current feasibility using ivermectin (Mectizan(®)) monotherapy

We review and analyze approaches over a 65 year period that have proven successful for onchocerciasis control in several different epidemiological settings. These include vector control with the goal of transmission interruption versus the use of mass drug administration using ivermectin (Mectizan(®)) monotherapy. Ivermectin has proven exceedingly effective because it is highly efficacious against Onchocerca volvulus microfilariae, the etiological agent of onchocercal skin and ocular disease and the infective stage for the vector. For these reasons, the drug was donated by the Merck Company for regional control programs in Africa and the Americas. Recurrent treatment with ivermectin at semi-annual intervals also impacts adult worms and result in loss of fecundity and increased mortality. Using a strategy of 6-monthly treatments with high coverage rates, the Onchocerciasis Elimination Program for the Americas has interrupted transmission in seven of the thirteen foci in the Americas and is on track to eliminate onchocerciasis in the region by 2015. Treatments given annually or semi-annually for 15-17 years in three hyperendemic onchocerciasis foci in Mali and Senegal also have resulted in a few infections in the human population with transmission levels below thresholds postulated for elimination. Follow-up evaluations did not detect any recrudescence of infection or transmission, suggesting that onchocerciasis elimination could be feasible with Mectizan(®) treatment in some endemic foci in Africa.

The Onchocerciasis Elimination Program for the Americas (OEPA)

Human onchocerciasis (river blindness) occurs in 13 foci distributed among six countries in Latin America (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela), where about 500,000 people are considered at risk. An effort to eliminate the disease from the region was launched in response to a specific resolution adopted by the PanAmerican Health Organization (PAHO) in 1991: to eliminate onchocerciasis from the region, as a public-health problem, by 2007. The effort took advantage of the donation of the drug Mectizan (ivermectin) by Merck & Co., Inc. In 1992, the Onchocerciasis Elimination Program for the Americas (OEPA) was launched, with its headquarters in Guatemala, to act as a technical and co-ordinating body of a multinational, multi-agency coalition that includes the endemic countries, PAHO, The Carter Center, Lions Clubs, the United States Centers for Disease Control and Prevention, The Bill and Melinda Gates Foundation, Merck & Co., Inc., and other partners. This public-private partnership facilitated the establishment of programmes for the semi-annual mass administration of Mectizan in the six countries with onchocerciasis. The aims were to (1) provide sustained treatments, with coverage reaching at least 85% of those eligible to receive the drug (in the 1845 endemic communities that are distributed within the 13 regional foci); (2) eliminate new morbidity caused by Onchocerca volvulus infection by 2007; and (3) eliminate transmission of the parasite wherever feasible. Significant progress has already been made in all six countries, each of which has active programmes with treatment coverages exceeding the target of 85%. The progress is being documented in accordance with certification guidelines for onchocerciasis elimination established by the World Health Organization. No new cases of onchocercal blindness are being reported in the region, and ocular disease attributable to O. volvulus has been eliminated from nine of the 13 foci. Treatment is no longer needed in Santa Rosa, Guatemala, where transmission has been eliminated, and will be halted in at least three other foci in 2008, as they confirm the interruption of transmission. Treatment efforts should now be concentrated on the five foci where significant transmission remains: Central (Guatemala), Amazonas/Roraima (Brazil), North-central (Venezuela), North-east (Venezuela) and South (Venezuela). Based upon the experience gained, the well-established operations and the success achieved so far, it seems reasonable to estimate that onchocerciasis could be eliminated from most of the remaining foci in the Americas by 2012. The protocol, criteria and deadline for stopping all onchocerciasis treatment in the region should soon be addressed by OEPA's Program Co-ordinating Committee (PCC), in co-ordination with the PAHO.

The Carter Center's assistance to river blindness control programs: establishing treatment objectives and goals for monitoring ivermectin delivery systems on two continents

Periodic mass treatment with ivermectin in endemic communities prevents eye and dermal disease due to onchocerciasis. As part of an international global partnership to control onchocerciasis, The Carter Center's Global 2000 River Blindness Program (GRBP) assists the ministries of health in ten countries to distribute ivermectin (Mectizan, donated by Merck & Co.). The GRBP priorities are to maximize ivermectin treatment coverage and related health education and training efforts, and to monitor progress through regular reporting of ivermectin treatments measured against annual treatment objectives and ultimate treatment goals (e.g., full coverage, which is defined as reaching all persons residing in at risk villages who are eligible for treatment). Since the GRBP began in 1996, more than 21.2 million ivermectin treatment encounters have been reported by assisted programs. In 1999, more than 6.6 million eligible persons at risk for onchocerciasis received treatment, which represented 96% of the 1999 annual treatment objective of 6.9 million, and 78% of the ultimate treatment goal in assisted areas.

Serologic and parasitologic studies of Entamoeba histolytica in El Salvador, 1974-1978

Serologic and parasitologic studies were done in El Salvador, C.A., from 1974-1978 to examine the reliability of the diagnosis of Entamoeba histolytica infection in an endemic area and to confirm the estimates of morbidity and mortality due to amebiasis. The results suggest that infection with E. histolytica is common, but the estimated prevalence is too high. Misdiagnosis occurring in hospital and public health laboratories was documented. Data collected from examining family members of persons with E. histolytica infection and disease indicate that most infections are asymptomatic, and support the hypothesis that estimates of morbidity and mortality rates are excessive.

A precipitin test for the diagnosis of human abdominal angiostrongyliasis

A precipitin reaction was observed when sera of cotton rats infected either naturally or experimentally with Angiostrongylus costaricensis were tested by gel double-diffusion against sera obtained from three biopsy-confirmed human cases of A. costaricensis. With immunoelectrophoresis, the antigen was demonstrated in the serum of infected rats. The antibody in the human serum was mostly of the IgG type. No cross reactions were seen with sera from individuals infected with the common intestinal helminths, or individuals serologically positive for Toxocara, A. cantonensis, Chagas' disease, amebiasis, leishmaniasis, toxoplasmosis, or syphilis.