Meaningful change: Defining the interpretability of changes in endpoints derived from interactive and mHealth technologies in healthcare and clinical research

Immersive, interactive and mHealth technologies are increasingly being used in clinical research, healthcare and rehabilitation solutions. Leveraging technology solutions to derive new and novel clinical outcome measures is important to the ongoing assessment of clinical interventions. While demonstrating statistically significant changes is an important element of intervention assessment, understanding whether changes detected reflect changes of a magnitude that are considered meaningful to patients is equally important. We describe methodologies used to determine meaningful change and recommend that these techniques are routinely included in the development and testing of clinical assessment and rehabilitation technology solutions.

Considerations for development of an evidence dossier to support the use of mobile sensor technology for clinical outcome assessments in clinical trials

BACKGROUND

Mobile sensors offer enormous potential for the collection of informative clinical endpoints in clinical trials to support regulatory decision making and product labelling. There are currently no specific guidelines on the information needed to enable regulators to review and accept proposed endpoints derived from mobile sensors for use in drug development trials.

OBJECTIVE

The purpose of this working group report is to recommend the structure and content of an evidence dossier intended to support whether a clinical endpoint derived from mobile sensor data is fit-for-purpose for use in regulatory submissions for drug approvals.

EVIDENCE DOSSIER

The structure and content of a dossier to provide evidence supporting the use of a sensor-derived clinical endpoint is described. Sections include clinical endpoint definition and positioning, the concept of interest, the context of use, clinical validation and interpretation, study implementation, and analytical validity with sensor performance verification in support of the selected sensor.

CONCLUSIONS

In the absence of definitive regulatory guidance, this report provides a considered approach to compiling a comprehensive body of evidence to justify acceptance of mobile sensors for support of new drug applications.

Objective measurement of sedentary behaviour using accelerometers

Background:

Sedentary behaviour (SB) is an important risk factor for a number of chronic diseases. Although gaps remain in our knowledge of the elements of SB most associated with reduced health outcomes, measuring SB is important, especially in less active patient populations where treatment-related changes may be seen first in changes in SB.

Methods:

We review current published work in the measurement of SB to make recommendations for SB measurement in clinical studies.

Results:

To help move our understanding of the area forward, we propose a set of derived measures of SB that can be easily understood and interpreted.

Conclusion:

Although there is more work required to determine and validate the most clinically relevant and sensitive measures of SB, there is enough understanding of how to measure SB to enable its inclusion in study protocols.

Minimization in crossover trials with non-prognostic strata: theory and practical application

To obtain meaningful results in any clinical trial, patients need to be allocated to treatments in such a way that valid analysis can be carried out. Balancing treatment groups before analysis is carried out is more desirable than trying to compensate for incomparability at a later date. Therefore, the development of allocation procedures to produce comparable groups in which prognostic factors are equally represented is important. Minimization, a deterministic allocation method, aims to ensure balance on such factors, particularly in small trials when traditional randomization methods are likely to fail. However, views on the use of conventional analysis following minimization are divided. The use of minimization in two randomised crossover trials is described where, in addition to the comparisons between randomised treatments, it was desired to have balance between groups based on differential trial procedures. Theoretical concerns about the use of minimization are not applicable in this setting, and therefore minimization is shown to be a useful technique for obtaining balance.

CD8(+) T cell knockout mice are less susceptible to Cowdria ruminantium infection than athymic, CD4(+) T cell knockout, and normal C57BL/6 mice

The role of T cells in immunity to Cowdria ruminantium was investigated by studying the responses to infection of normal, athymic, CD4(+) T cell knock out (KO) and CD8(+) T cell KO C57BL/6 mice. Normal C57BL/6 mice could be immunized by infection and treatment, and immunity was adoptively transferable from immune to naive mice by splenocytes. Following infection, athymic mice died sooner than normal mice (P=0.0017), and could not be immunized by infection and treatment. CD4(+) T cell KO mice were as susceptible to infection as normal mice and could be immunized by infection and treatment. In contrast, CD8(+) T cell KO mice were less susceptible than normal and CD4(+) T cell KO mice and 43% self-cured, while those that died did so after a prolonged incubation period. Antibody responses to C. ruminantium were CD4(+) T cell dependent, because responses were detected in immune normal and CD8(+) T cell KO mice but not in immune CD4(+) KO mice (P=0.005). Since CD8(+) T cell KO mice were less susceptible to infection, and since CD4(+) T cell KO mice could be immunized, it can be concluded that immunity to C. ruminantium can be mediated by both CD4(+) and CD8(+) T cells.

A polarized Th1 type immune response to Cowdria ruminantium infection is detected in immune DBA/2 mice

Immune responses to Cowdria ruminantium, an intracellular organism that causes heartwater in domestic ruminants, were characterized in a DBA/2 mouse model. Immunity induced by infection and treatment was adoptively transferable by splenocytes and could be abrogated by in vivo depletion of T cells but not by inhibition of nitric oxide synthase using NG-monomethyl-L-arginine. IgG2a and IgG2b C. ruminantium-specific responses were detected in immune mice. Culture supernatants of splenocytes from immune DBA/2 mice, which were stimulated with crude C. ruminantium antigens or recombinant major antigenic proteins 1 or 2, contained significant levels of interferon (IFN)-gamma and interleukin (IL)-6, but insignificant levels of IL-1alpha, IL-2, IL-4, IL-5, IL-10, IL-12, tumor necrosis factor-alpha (TNF), and nitric oxide. A similar response was detected during primary infection, although IFN-gamma levels decreased significantly during clinical illness and then increased following natural or antibiotic-aided recovery. These data support the conclusion that protective immunity to C. ruminantium in DBA/2 mice is mediated by T cells and is associated with a polarized T helper 1 type of immune response. This murine model could be utilized to screen for protective C. ruminantium antigens that provoke Th1 type immune responses and for evaluation of these antigens in recombinant vaccines against heartwater.

Neutralization of bovine concanavalin-A T cell supernatant-mediated anti-Cowdria ruminantium activity with antibodies specific to interferon gamma but not to tumor necrosis factor

In an earlier study we demonstrated that Concanavalin-A stimulated bovine T cell supernatants inhibited the growth of Cowdria ruminantium in bovine endothelial cells in vitro. An investigation was conducted to identify the cytokines which were responsible for this growth inhibition. Addition of antiserum against bovine interferon gamma (IFN gamma) reproducibly neutralized the inhibitory effect of the T cell supernatants, whereas addition of antisera against bovine tumor necrosis factor alpha (TNF alpha) had no effect. The inhibitory effect of IFN gamma on C. ruminantium growth was not mediated by the production of nitric oxide as there was no detectable difference in nitric oxide levels in cultures that were supplemented with T cell supernatants compared with those that were not. The IFN gamma mediated anti-C. ruminantium effect highlights the importance of cell mediated immune responses in control of these infections and in particular incriminates the protective role of T cells, or cells that secrete IFN gamma.

Conconavalin A-stimulated bovine T-cell supernatants inhibit growth of Cowdria ruminantium in bovine endothelial cells in vitro

Conconavalin A-stimulated bovine T-cell supernatants inhibited the growth of Cowdria ruminantium in bovine endothelial cells in vitro but did not affect their entry. This finding represents one mechanism by which T cells may control C. ruminantium multiplication and hence affect the severity of disease.

The development of antibody to Cowdria ruminantium in mice and its role in heartwater disease

DBA/2 and Balb/c mice were used as a model to study the immune responses to Cowdria ruminantium. Both strains of mice were inoculated with 1, 10 or 100 LD50 of the Crystal Springs strain of C. ruminantium. Antibody to C. ruminantium started to develop in the second week post-inoculation and the titre of the antibody was dependent on the inoculation dose of C. ruminantium. The possible role of antibody in heartwater disease was studied by in vitro neutralization assays using both mouse sera and bovine sera. Results of these tests show that hyperimmune serum from both DBA/2 and Balb/c mice had the ability to neutralize infection in vitro, with the DBA/2 serum showing a greater neutralizing effect. Two bovine sera, one from a laboratory infected animal and one a pool from two animals infected in the field also gave a neutralizing effect.

Improved culture conditions for Cowdria ruminantium (Rickettsiales), the agent of heartwater disease of domestic ruminants

The causal agent of heartwater disease of domestic ruminants, Cowdria ruminantium, can, with difficulty, be isolated and passaged in lines of bovine endothelial cells grown in the presence of the Glasgow modification of Eagle's minimal essential medium. However, when Leibovitz's L-15 medium supplemented with 0.45% glucose at pH 6.0-6.5 is used as maintenance medium for these cells, isolation and serial passage may routinely be achieved.

In vitro isolation of Cowdria ruminantium from plasma of infected ruminants

A new and simple technique for isolation of C. ruminantium in bovine and ovine vascular endothelial cells (aorta, pulmonary artery) is described. Unlike previous studies, no efforts were made to retard cell growth by irradiation or chemicals. Instead, heparin-derived plasma samples obtained from only those animals exhibiting prolonged or extremely high temperatures were used. In this way, C. ruminantium was isolated from 27 of 37 samples (73%) and from 22 of 26 animals (85%). A total of six Zimbabwean stocks of C. ruminantium were isolated in cell culture.

Isolation and characterization of bovine Theileria parasites in Zimbabwe

Theilerial parasites of cattle were isolated by a variety of methods from the Harare area of Zimbabwe. Parasite stocks were established in lymphoid cell cultures and as cryopreserved sporozoite stabilates in the laboratory. Fourteen stocks in culture were characterized by testing them with monoclonal antibodies (MAb) raised against T. parva parva and T. parva lawrencei antigen. Two of these stocks had profiles similar to T. taurotragi isolates from East Africa, the other stocks had profiles similar to T. parva parva, however, many of them failed to bind MAb No. 7, and this may be a distinctive feature for T. parva bovis. Three T. p. bovis stocks were titrated by injecting different doses of the respective stabilates into pairs of cattle. Reactions ranged from severe to inapparent according to the stocks and dose used, but no fatal reactions were recorded, even at the highest dose rate. On recovery, all cattle were given homologous and then heterologous challenge. The results of the latter challenge showed that the Boleni stock gave good cross-protection against challenge with two other Zimbabwean stocks. This stock may therefore be a candidate for immunizing cattle, under field conditions, to protect them against T. p. bovis in Zimbabwe. Non-pathogenic strains of T. p. bovis may be difficult to distinguish from T. taurotragi unless cross-challenge experiments can be conducted and/or MAb profiles have been made. An improved serological test is needed to differentiate antibodies to these parasites in the sera of recovered cattle.