Performance of laser-derived imaging for assessing digital perfusion in clinical trials of systemic sclerosis-related digital vasculopathy: A systematic literature review

Assessment of digital perfusion as a surrogate outcome in Raynaud's phenomenon clinical trials

OBJECTIVES

Measurement of digital perfusion, sometimes coupled with a cold challenge, has been widely used as an objective outcome in trials evaluating drug therapies in RP, in addition to patient-reported outcomes or to establish the proof-of-concept in preliminary studies. However, whether digital perfusion is a valid surrogate for clinical outcomes in RP trials has never been explored. The principal aim of this study was to evaluate the potential surrogacy of digital perfusion, by combining individual-level and trial-level data.

METHODS

We used individual data from a series of n-of-1 trials, and trial data from a network meta-analysis. We estimated individual-level surrogacy through coefficients of determination between digital perfusion and clinical outcomes (R2ind). We further calculated the coefficients of determination between treatment effect on the clinical outcomes and on digital perfusion, at the individual level (R2TEind) and at the trial level (R2trial), using non-weighted linear regression, with their 95% CI calculated through bootstrapping.

RESULTS

Results from 33 patients and 24 trials were included in the final analysis. At the individual level, there was no correlation between digital perfusion and clinical outcomes at rest and in response to various cooling tests (the highest R2ind was 0.03 [-0.07, 0.09]), and R2TEind was also very low 0.07 (0, 0.29). At the trial level, the highest value of R2trial was 0.1 (0, 0.477).

CONCLUSIONS

Digital perfusion, at rest or in response to a cold challenge, and whatever the method used, does not fulfil the criteria of a valid surrogate for existing patient-reported outcomes in RP trials.

Raynaud phenomenon and microvasculopathy in systemic sclerosis: multi-modality imaging for diagnosis and evaluation

PURPOSE OF REVIEW

To describe the clinical significance of and the diagnostic approach to Raynaud phenomenon (RP) in the peripheral extremities and the heart.

RECENT FINDINGS

Nailfold capillaroscopy has recently been standardized in an expert consensus paper. Abnormal capillaroscopy in combination with specific autoantibody profiles and clinical signs are highly predictive of progression of RP to systemic sclerosis (SSc). Magnetic resonance imaging (MRI) can also perform tissue characterization of both the extremities and the heart. Microvascular wall abnormalities detected using nailfold capillaroscopy in patients with SSc may lead to deposition of erythrocyte-derived iron, due to microhemorrhages, which may predispose to fibrosis. MRI can assess the presence of iron using T2∗ measurements.

SUMMARY

RP is a hallmark of the microvasculopathy in SSc and can affect both the peripheral extremities and the heart. Nailfold capillaroscopy is the current gold standard for the evaluation of the peripheral microvasculature. Other imaging modalities include thermography, laser Doppler-derived methods, 99m Tc-pertechnetate hand perfusion scintigraphy, power Doppler ultrasonography, dynamic optical coherence tomography, MRI, and photoacoustic imaging, but these are currently not widely used. Cardiac RP can be investigated with positron emission tomography or cardiovascular magnetic resonance, with the latter offering the additional possibility of tissue characterization and iron content quantification secondary to microhemorrhages.

Domain reporting in systemic sclerosis-related Raynaud's phenomenon: An OMERACT scoping review

BACKGROUND

Raynaud's phenomenon (RP) is a cardinal feature of SSc and is associated with significant disease-related morbidity that impacts on quality of life. The assessment of SSc-RP is challenging. The aim of this scoping review was to evaluate the outcome domains studied and outcome measures used in clinical studies of SSc-RP.

METHODS

Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials were used to identify randomized control trials (RCTs), quasi-randomized studies, case-control studies, prospective and retrospective cohort studies, case series, and cross-sectional studies of adult participants with SSc-associated RP, written in English. A minimum of 25 participants for studies of imaging modalities and 40 participants for questionnaire-based studies was required for inclusion. Basic laboratory and genetic studies were excluded. No limitations were imposed based on intervention, comparator, or study setting. Study characteristics and primary and secondary target domains in each study were recorded.

RESULTS

58 studies (24 randomized clinical trials) were included in the final analysis. The commonest domains captured were severity of attacks (n=35), frequency of attacks (n=28), and duration of attacks (n=19). Objective assessments of digital perfusion were also commonly used in studies of SSc-RP.

CONCLUSION

The outcome domains and the associated outcomes used to assess the impact of SSc-RP in research studies are broad and have varied across studies. The results of this study will inform the OMERACT Vascular Disease in Systemic Sclerosis Working Group to establish a core set of disease domains encompassing the impact of RP in SSc.

Domain reporting in Systemic Sclerosis-Related Digital Ulcers: An OMERACT Scoping Review

BACKGROUND

Digital ulcers (DUs) are a major cause of pain and disability in patients with systemic sclerosis (SSc). The aim of this scoping review was to evaluate the outcome domains used in studies of SSc-associated DUs.

METHODS

Electronic databases (EMBASE, MEDLINE and the Cochrane Library) were searched for articles written (1947 onwards) in English relating to SSc-DUs. A minimum of 15 participants for studies of imaging and 25 participants for questionnaire-based studies was required for inclusion. Information on all primary and secondary domains was extracted.

RESULTS

4869 manuscripts were identified, of which 40 met the eligibility criteria and were included in the synthesis. Most studies were randomized controlled trials (n=13), or prospective (n=12)/retrospective (n=8) observational studies. Interventions included oral or intravenous drugs (n=25), topical/local treatments (n=5), and surgical interventions (n=2). Approximately half the studies assessed either the count/number of DUs (n=23) and/or improvement in DUs (n=20). Functional impact of DUs was examined in 25% (n=10) of studies. Other domains were related to complications of DUs (n=7), pain (n=6), health-related quality of life (n=4), microvascular assessment/pathophysiology (n=4), global assessment of DUs (n=2), and histopathology (n=1).

CONCLUSION

This scoping review identified a broad range of disease-related domains used to study SSc-DUs. There is significant heterogeneity in these domains. These data will inform the ongoing work of the OMERACT Vascular Disease in Systemic Sclerosis Working Group to define a core set of disease broad domains to capture the burden of DUs in SSc.

Hyperspectral imaging in systemic sclerosis-associated Raynaud phenomenon

BACKGROUND/PURPOSE

Lack of robust, feasible, and quantitative outcomes impedes Raynaud phenomenon (RP) clinical trials in systemic sclerosis (SSc) patients. Hyperspectral imaging (HSI) non-invasively measures oxygenated and deoxygenated hemoglobin (oxyHb and deoxyHb) concentrations and oxygen saturation (O2 sat) in the skin and depicts data as oxygenation heatmaps. This study explored the potential role of HSI in quantifying SSc-RP disease severity and activity.

METHODS

Patients with SSc-RP (n = 13) and healthy control participants (HC; n = 12) were prospectively recruited in the clinic setting. Using a hand-held camera, bilateral hand HSI (HyperMed™, Waltham, MA) was performed in a temperature-controlled room (22 °C). OxyHb, deoxyHb, and O2 sat values were calculated for 78-mm2 regions of interest for the ventral fingertips and palm (for normalization). Subjects underwent a cold provocation challenge (gloved hand submersion in 15 °C water bath for 1 min), and repeated HSI was performed at 0, 10, and 20 min. Patients completed two patient-reported outcome (PRO) instruments: the Raynaud Condition Score (RCS) and the Cochin Hand Function Scale (CHFS) for symptom burden assessment. Statistical analyses were performed using the Mann-Whitney U test and a mixed effects model (Stata, College Station, TX).

RESULTS

Ninety-two percent of participants were women in their 40s. For SSc-RP patients, 69% had limited cutaneous SSc, the mean ± SD SSc duration was 11 ± 5 years, and 38% had prior digital ulcers-none currently. Baseline deoxyHb was higher, and O2 sat was lower, in SSc patients versus HC (p < 0.05). SSc patients had a greater decline in oxyHb and O2 sat from baseline to time 0 (after cold challenge) with distinct rewarming oxyHb, O2 sat, and deoxyHb trajectories versus HCs (p < 0.01). There were no significant correlations between oxyHb, deoxyHb, and O2 sat level changes following cold challenge and RCS or CHFS scores.

CONCLUSION

Hyperspectral imaging is a feasible approach for SSc-RP quantification in the clinic setting. The RCS and CHFS values did not correlate with HSI parameters. Our data suggest that HSI technology for the assessment of SSc-RP at baseline and in response to cold provocation is a potential quantitative measure for SSc-RP severity and activity, though longitudinal studies that assess sensitivity to change are needed.

Correlation between Microvascular Damage and Internal Organ Involvement in Scleroderma: Focus on Lung Damage and Endothelial Dysfunction

BACKGROUND

Systemic sclerosis (SSc) is an incurable connective tissue disease characterized by decreased peripheral blood perfusion due to microvascular damage and skin thickening/hardening. The microcirculation deficit is typically secondary to structural vessel damage, which can be assessed morphologically and functionally in a variety of ways, exploiting different technologies.

OBJECTIVE

This paper focuses on reviewing new studies regarding the correlation between microvascular damage, endothelial dysfunction, and internal organ involvement, particularly pulmonary changes in SSc.

METHODS

We critically reviewed the most recent literature on the correlation between blood perfusion and organ involvement.

RESULTS

Many papers have demonstrated the link between structural microcirculatory damage and pulmonary involvement; however, studies that have investigated correlations between microvascular functional impairment and internal organ damage are scarce. Overall, the literature supports the correlation between organ involvement and functional microcirculatory impairment in SSc patients.

CONCLUSIONS

Morphological and functional techniques appear to be emerging biomarkers in SSc, but obviously need further investigation.

Kinetics of response to iloprost evaluated by laser speckle contrast analysis in systemic sclerosis

OBJECTIVE

Iloprost (ILO) is recommended for the treatment of systemic sclerosis (SSc) microangiopathy, but there is no common consensus on its optimal dosage. The aim of this study is to evaluate the kinetics of response to ILO administered in a daily outpatient scheme in SSc subjects using laser speckle contrast analysis (LASCA).

METHOD

Adult SSc patients in stable therapy with ILO administered for 6 h for 2 consecutive days every 4 weeks were enrolled. Peripheral finger perfusion was assessed by LASCA. Each patient underwent five LASCA evaluations: before and after each day of ILO (D1pre, D1post, D2pre, and D2post) and after 4 weeks (D30).

RESULTS

Twenty-seven SSc patients (77.8% female, mean age 61.5 years) were enrolled. LASCA showed an increase in perfusion at the end of each ILO course, but on the second day (both D1pre vs D2pre and D2pre vs D2post) the increase was no longer significant in half of the fingers. Moreover, compared to D1post, at the beginning of the second ILO day most of the fingers had already shown a significant reduction in perfusion. After 1 month, there were no statistically significant differences between the perfusion values of D1pre and D30.

CONCLUSION

This LASCA study highlights the transience of the vasoactive effect of ILO, with a perfusion benefit that is completely lost after 1 month. The brevity of the perfusion effect of ILO and the use of LASCA are elements to consider in the design of future SSc trials to determine the optimal ILO dosage.

Raynaud's phenomenon and digital ulcers: advances in evaluation and management

PURPOSE OF REVIEW

The aim of this review is to give an update on advances in evaluation and management of systemic sclerosis (SSc)-related Raynaud's phenomenon and digital ulceration, focusing on reports from the last 18 months. The increasing recognition of the huge impact of Raynaud's phenomenon and of digital ulceration on the everyday lives of patients with SSc has sparked enthusiasm internationally to develop better outcome measures and better treatments, and so a review is timely.

RECENT FINDINGS

There have been recent advances in the development of patient reported outcome instruments [e.g. the Hand Disability in Systemic Sclerosis-Digital Ulcers (HDISS-DU) instrument] and also in noninvasive imaging techniques, including thermography and laser Doppler methods. Improved outcome measures will facilitate future clinical trials, both early phase proof-of-concept and later phase trials. New insights have been gained into mechanisms of action and methods of administration of 'conventional' therapies, for example phosphodiesterase inhibitors and intravenous prostanoids. New treatment approaches are being investigated, including topical and procedural therapies.

SUMMARY

Clinicians can look forward to seeing these advances translating into clinical benefit over the next 5 years. To help ensure this, they should strive whenever possible to recruit patients with SSc-related digital vasculopathy into observational studies and clinical trials.

Temperature response to cold challenge and mobile phone thermography as outcome measures for systemic sclerosis-related Raynaud's phenomenon

Objectives: Objective outcome measures of systemic sclerosis (SSc)-related Raynaud's phenomenon (RP) are badly needed. Our objectives were to validate the thermographic response to a standard hand cold challenge as an outcome measure by assessing sensitivity to change, and to explore mobile phone thermography as a feasible, ambulatory tool.Method: Twelve patients with an SSc-spectrum disorder admitted for intravenous iloprost infusions underwent a standard cold challenge before and after one infusion. Thermographic measurements included area under the rewarming curve (AUC) and maximum rewarming temperature (MAX). Before and during another infusion, each patient underwent monitoring of finger skin temperature by two methods: continuous thermocouple recording (standard method) and mobile phone thermography.Results: All cold challenge summary measures, including AUC and MAX, increased after iloprost (most not significantly). However, when the response curves were modelled after averaging across fingers (linear mixed models, three versions), significant change was detected. For example, with Model 1 (no interaction between period and time), temperature was on average 1.67ºC [95% confidence interval (CI) 1.49-1.85, p < 0.001] higher post-iloprost. Mobile phone and thermocouple temperature measurements showed a strong estimated latent correlation (0.88, 95% CI 0.81-0.92). The estimated increases/hour were 0.25ºC (95% CI 0.05-0.45) for the thermocouple and 0.36ºC (95% CI 0.13-0.60) for mobile phone thermography.Conclusion: Our pilot study suggests that the thermographic response to a cold challenge is sensitive to change and mobile phone thermography could bring feasibility to thermographic parameters as outcome measures in later-phase, large-scale, community-based clinical trials of RP.

Raynaud's phenomenon

Raynaud's phenomenon (RP) is a common vasospastic condition which affects ~5% of the general population. The majority of individuals have primary RP; however, Raynaud's can also occur secondary to a broad range of underlying medical conditions and drug therapies. RP is a cardinal feature in patients with systemic sclerosis and is often the earliest symptom of the disease. Unlike primary RP, patients with secondary RP can develop persistent digital ischaemia, including ulcers and gangrene. Patients require a comprehensive clinical assessment and investigation, in particular, the detection of autoantibodies and nailfold capillaroscopic abnormalities. Non-pharmacological management is indicated in all patients. There are a wide range of available drug therapies to treat RP, including when complicated by digital ulceration, and surgical intervention is sometimes required. Future research is needed to understand the complex pathogenesis of RP and to measure the impact and severity of RP to develop optimised approaches to management.