Development and validation of the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI): a novel instrument to quantify organ damage in systemic sclerosis

Objective

We sought to develop the first Damage Index (DI) in systemic sclerosis (SSc).

Methods

The conceptual definition of ‘damage’ in SSc was determined through consensus by a working group of the Scleroderma Clinical Trials Consortium (SCTC). Systematic literature review and consultation with patient partners and non-rheumatologist experts produced a list of potential items for inclusion in the DI. These steps were used to reduce the items: (1) Expert members of the SCTC (n=331) were invited to rate the appropriateness of each item for inclusion, using a web-based survey. Items with >60% consensus were retained; (2) Using a prospectively acquired Australian cohort data set of 1568 patients, the univariable relationships between the remaining items and the endpoints of mortality and morbidity (Physical Component Summary score of the Short Form 36) were analysed, and items with p<0.10 were retained; (3) using multivariable regression analysis, coefficients were used to determine a weighted score for each item. The DI was externally validated in a Canadian cohort.

Results

Ninety-three (28.1%) complete survey responses were analysed; 58 of 83 items were retained. The univariable relationships with death and/or morbidity endpoints were statistically significant for 22 items, with one additional item forced into the multivariable model by experts due to clinical importance, to create a 23-item weighted SCTC DI (SCTC-DI). The SCTC-DI was predictive of morbidity and mortality in the external cohort.

Conclusions

Through the combined use of consensus and data-driven methods, a 23-item SCTC-DI was developed and retrospectively validated.

The role of inflammatory markers in assessment of disease activity in systemic sclerosis

OBJECTIVES

The role of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the assessment of disease activity in systemic sclerosis (SSc) remains controversial. We sought to evaluate the relationship between clinical features of SSc and raised inflammatory markers and to determine if changes in ESR and CRP reflect changes in other disease features over time.

METHODS

One thousand, five hundred and forty-five patients enrolled in the Australian Scleroderma Cohort Study were observed over a mean 3.52±2.91 years and assessed at 6,119 study visits. Generalised estimating equations were used to determine the relationship between ESR≥20mm/hr and CRP≥5mg/L and features of disease. The associations between change in inflammatory markers and change in skin scores and respiratory function tests were analysed.

RESULTS

Overall, there was a significant association between raised ESR and forced vital capacity (FVC)<80% predicted, diffusing capacity of the lung (DLCO)<80% predicted, pulmonary arterial hypertension (PAH), body mass index (BMI), proximal muscle strength, anaemia, and hypocomplementaemia (p<0.05). Raised CRP was significantly associated with modified Rodnan Skin Score>20, FVC<80%, DLCO<80%, PAH, digital ulcers, BMI, synovitis, tendon friction rub, anaemia, and hypocomplementaemia (p<0.05). A significant deterioration in respiratory function tests (RFTs) was associated with a 2-fold increase in both ESR and CRP (p<0.05).

CONCLUSIONS

Raised inflammatory markers are associated with pulmonary, cutaneous and musculoskeletal manifestations of SSc. Rising inflammatory markers are correlated with declining respiratory function tests. This suggests inflammatory markers have a role in the assessment of SSc disease activity.

Quantifying the direct public health care cost of systemic sclerosis: A comprehensive data linkage study

To quantify the direct healthcare cost of systemic sclerosis (SSc) and identify its determinants. Healthcare use was captured through data linkage, wherein clinical and medication data for SSc patients from the state of Victoria enrolled in the Australian Scleroderma Cohort Study were linked with the Victorian hospital admissions and emergency presentations data sets, and the Medicare Benefits Schedule which contains all government subsidized ambulatory care services, for the period 2011-2015. Medication cost was determined from the Pharmaceutical Benefits Scheme. Costs were extrapolated to all Australian SSc patients based on SSc prevalence of 21.1 per 100,000 and an Australian population of 24,304,682 in 2015. Determinants of healthcare cost were estimated using logistic regression. Total healthcare utilization cost to the Australian government extrapolated to all Australian SSc patients from 2011 to 2015 was Australian Dollar (AUD)$297,663,404.77, which is an average annual cost of AUD$59,532,680.95 (US Dollar [USD]$43,816,040.08) and annual cost per patient of AUD$11,607.07 (USD$8,542.80). Hospital costs, including inpatient hospitalization and emergency department presentations, accounted for the majority of these costs (44.4% of total), followed by medication cost (31.2%) and ambulatory care cost (24.4%). Pulmonary arterial hypertension (PAH) and gastrointestinal (GIT) involvement were the major determinants of healthcare cost (OR 2.3 and 1.8, P = .01 for hospitalizations; OR 2.8 and 2.0, P = .01 for ambulatory care; OR 7.8 and 1.6, P < .001 and P = .03 for medication cost, respectively). SSc is associated with substantial healthcare utilization and direct economic burden. The most costly aspects of SSc are PAH and GIT involvement.

Early Mortality in a Multinational Systemic Sclerosis Inception Cohort

OBJECTIVE

To determine mortality and causes of death in a multinational inception cohort of subjects with systemic sclerosis (SSc).

METHODS

We quantified mortality as standardized mortality ratio (SMR), years of life lost, and percentage mortality in the first decade of disease. The inception cohort comprised subjects recruited within 4 years of disease onset. For comparison, we used a prevalent cohort, which included all subjects irrespective of disease duration at recruitment. We determined a single primary cause of death (SSc related or non-SSc related) using a standardized case report form, and we evaluated predictors of mortality using multivariable Cox regression.

RESULTS

In the inception cohort of 1,070 subjects, there were 140 deaths (13%) over a median follow-up of 3.0 years (interquartile range 1.0-5.1 years), with a pooled SMR of 4.06 (95% confidence interval [95% CI] 3.39-4.85), up to 22.4 years of life lost in women and up to 26.0 years of life lost in men, and mortality in the diffuse disease subtype of 24.2% at 8 years. In the prevalent cohort of 3,218 subjects, the pooled SMR was lower at 3.39 (95% CI 3.06-3.71). In the inception cohort, 62.1% of the primary causes of death were SSc related. Malignancy, sepsis, cerebrovascular disease, and ischemic heart disease were the most common non-SSc-related causes of death. Predictors of early mortality included male sex, older age at disease onset, diffuse disease subtype, pulmonary arterial hypertension, and renal crisis.

CONCLUSION

Early mortality in SSc is substantial, and prevalent cohorts underestimate mortality in SSc by failing to capture early deaths, particularly in men and those with diffuse disease.

Epidemiology and disease characteristics of systemic sclerosis-related pulmonary arterial hypertension: results from a real-life screening programme

BACKGROUND

Pulmonary arterial hypertension (PAH) is the leading cause of death in systemic sclerosis (SSc). Annual screening with echocardiogram (ECHO) is recommended. We present the methodological aspects of a PAH screening programme in a large Australian SSc cohort, the epidemiology of SSc-PAH in this cohort, and an evaluation of factors influencing physician adherence to PAH screening guidelines.

METHODS

Patient characteristics and results of PAH screening were determined in all patients enrolled in a SSc longitudinal cohort study. Adherence to PAH screening guidelines was assessed by a survey of Australian rheumatologists. Summary statistics, chi-square tests, univariate and multivariable logistic regression were used to determine the associations of risk factors with PAH.

RESULTS

Among 1636 patients with SSc, 194 (11.9%) had PAH proven by right-heart catheter. Of these, 160 were detected by screening. The annual incidence of PAH was 1.4%. Patients with PAH diagnosed on subsequent screens, compared with patients in whom PAH was diagnosed on first screen, were more likely to have diffuse SSc (p = 0.03), be in a better World Health Organisation (WHO) Functional Class at PAH diagnosis (p = 0.01) and have less advanced PAH evidenced by higher mean six-minute walk distance (p = 0.03), lower mean pulmonary arterial pressure (p = 0.009), lower mean pulmonary vascular resistance (p = 0.006) and fewer non-trivial pericardial effusions (p = 0.03). Adherence to annual PAH screening using an ECHO-based algorithm was poor among Australian rheumatologists, with less than half screening their patients with SSc of more than ten years disease duration.

CONCLUSION

PAH is a common complication of SSc. Physician adherence to PAH screening recommendations remains poor. Identifying modifiable barriers to screening may improve adherence and ultimately patient outcomes.

The association of low complement with disease activity in systemic sclerosis: a prospective cohort study

Background

In some rheumatic diseases such as systemic lupus erythematosus (SLE), low serum complement (‘hypocomplementaemia’) is a feature of active disease. However, the role of hypocomplementaemia in systemic sclerosis (SSc) is unknown. We sought to determine the frequency, clinical associations and relationship to disease activity of hypocomplementaemia in SSc.

Methods

The study included 1140 patients fulfilling the 2013 American College of Rheumatology criteria for SSc. Demographic, serological and clinical data, obtained prospectively through annual review, were analysed using univariable methods. Linear and logistic regression, together with generalised estimating equations, were used to determine the independent correlates of hypocomplementaemia ever, and at each visit, respectively.

Results

At least one episode of hypocomplementaemia (low C3 and/or low C4) occurred in 24.1 % of patients over 1893 visits; these patients were more likely to be seropositive for anti-ribonucleoprotein (OR = 3.8, p = 0.002), anti-Ro (OR = 2.2, p = 0.002), anti-Smith (OR = 6.3, p = 0.035) and anti-phospholipid antibodies (OR = 1.4, p = 0.021) and were more likely to display features of overlap connective tissue disease, in particular polymyositis (OR = 16.0, p = 0.012). However, no association was found between hypocomplementaemia and either the European Scleroderma Study Group disease activity score or any of its component variables (including erythrocyte sedimentation rate) in univariate analysis. Among patients with SSc overlap disease features, those who were hypocomplementaemic were more likely to have digital ulcers (OR = 1.6, p = 0.034), tendon friction rubs (OR = 2.4, p = 0.037), forced vital capacity <80 % predicted (OR = 2.9, p = 0.008) and lower body mass index (BMI) (OR for BMI = 0.9, p < 0.0005) at that visit, all of which are features associated with SSc disease activity and/or severity.

Conclusions

While hypocomplementaemia is not associated with disease activity in patients with non-overlap SSc, it is associated with some features of increased SSc disease activity in patients with overlap disease features.

Risk factors for development of pulmonary arterial hypertension in Australian systemic sclerosis patients: results from a large multicenter cohort study

BACKGROUND

Pulmonary arterial hypertension (PAH) is the leading cause of mortality in patients with systemic sclerosis (SSc). We sought to determine the incidence, prevalence and risk factors for PAH development in a large Australian SSc cohort.

METHODS

PAH was diagnosed on right heart catheterisation (mPAP >25 and PAWP <15 mmHg at rest). Patients with PH secondary to interstitial lung disease (ILD; defined as abnormal HRCT scan and FVC < 60 %) were excluded. Summary statistics, chi-square tests, univariate and multivariable logistic regression along with post-estimation diagnostics were used to determine the associations of different combinations of risk factors with PAH.

RESULTS

Among 1579 SSc patients, 8.4 % (132 patients) were diagnosed with PAH over a mean (±SD) follow-up of 3.2 (±2.5) years. The incidence of PAH in this cohort was 0.7 % per annum. Of these, 68.9 % had limited disease subtype (lcSSc). In multivariable regression analysis, the presence of anti-centromere antibody (ACA) (OR 1.6, 95 % CI 1.1-2.5, p = 0.03), oesphageal stricture (OR 2.0, 95 % CI 1.2-3.3, p = 0.006), calcinosis (OR 1.9, 95 % CI 1.2-2.9, p = 0.003), sicca symptoms (OR 1.6, 95 % CI 1.1-2.5, p = 0.03), mild ILD (OR 2.3, 95 % CI 1.5-3.7, p < 0.001) and digital ulcers (OR 1.6, 95 % CI 1.0-2.4, p = 0.03) were predictive of PAH. This model had an area under the curve of 0.7 and concordance of 91.8 %. When analysed by disease subtype, the presence of calcinosis (OR 2.2, 95 % CI 1.4-3.7, p = 0.01), sicca symptoms (OR 2.6, 95 % CI 1.5-4.6, p = 0.001), mild ILD (OR 2.3, 95 % CI 1.4-3.8, p = 0.001) and digital ulcers (OR 1.9, 95 % CI 1.2-3.7, p = 0.01) were predictive of PAH in lcSSc; and oesophageal stricture (OR 4.4, 95 % CI 1.9-10.5, p = 0.001), mild ILD (OR 2.8, 95 % CI 1.2-6.8, p = 0.02) and ACA (OR 5.2, 95 % CI 1.8-14.8, p = 0.002) were predictive of PAH in dcSSc.

CONCLUSIONS

The incidence and prevalence of PAH in this cohort are 0.7 % per annum and 8.4 %, respectively. The clinical-serologic risk factors for PAH differ based on disease subtype. In both subtypes, mild ILD is associated with PAH, suggesting the possibility of common pathogenic mechanisms underlying both of these disease manifestations. This model identifies a subset of patients at an appreciably higher risk of developing PAH, who should be screened and would in future, benefit from preventative therapies.

Cost savings with a new screening algorithm for pulmonary arterial hypertension in systemic sclerosis

BACKGROUND

Screening for pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc) is now standard care in this disease. The existing Australian Scleroderma Interest Group algorithm (ASIGSTANDARD ) is based on transthoracic echocardiography (TTE) and pulmonary function tests (PFT). Recently, ASIG has derived and validated a new screening algorithm (ASIGPROPOSED ) that incorporates N-terminal pro-B-type natriuretic peptide level together with PFT in order to decrease reliance on TTE, which has some limitations. Right heart catheterisation (RHC) remains the gold standard for the diagnosis of PAH in patients who screen 'positive'.

AIM

To compare the cost of PAH screening in SSc with ASIGSTANDARD and ASIGPROPOSED algorithms.

METHODS

We applied both ASIGSTANDARD and ASIGPROPOSED algorithms to 643 screen-naïve SSc patients from the Australian Scleroderma Cohort Study (ASCS), assuming a PAH prevalence of 10%. We compared the costs of screening, the number of TTE required and both the total number of RHC required and the number of RHC needed to diagnose one case of PAH, and costs, according to each algorithm. We then extrapolated the costs to the estimated total Australian SSc population.

RESULTS

In screen-naïve patients from the ASCS, ASIGPROPOSED resulted in 64% fewer TTE and 10% fewer RHC compared with ASIGSTANDARD , with $1936 (15%) saved for each case of PAH diagnosed. When the costs were extrapolated to the entire Australian SSc population, there was an estimated screening cost saving of $946 000 per annum with ASIGPROPOSED , with a cost saving of $851 400 in each subsequent year of screening.

CONCLUSIONS

ASIGPROPOSED substantially reduces the number of TTE and RHC required and results in substantial cost savings in SSc-PAH screening compared with ASIGSTANDARD .

Determinants of unemployment amongst Australian systemic sclerosis patients: results from a multicentre cohort study

OBJECTIVES

We sought to assess employment status, risk factors for unemployment and the associations of unemployment with patients' health related quality of life (HRQoL).

METHODS

All patients enrolled in a systemic sclerosis (SSc) longitudinal cohort study, completed an employment questionnaire on enrolment. Clinical manifestations were defined based on presence at the time of enrolment. Summary statistics, chi-square tests, univariate and multivariable logistic regression were used to determine the associations of various risk factors with employment.

RESULTS

Among 1587 SSc patients, 160 (20%) were unemployed at the time of cohort enrolment excluding retired patients. Of these, 63% had limited disease subtype. Mean (±SD) age at enrollment was 51.9 (±10.4) years; 13 years below the average retirement age in Australia. Mean (±SD) disease duration at recruitment was 11.1 (±10.9) years. Multivariable regression analysis revealed the presence of digital amputation (OR 3.9, 95%CI 1.7-9.1, p=0.002), diffuse disease subtype (OR 2.2, 95%CI 1.3-3.5, p-value=0.002), sicca symptoms (OR 2.7, 95%CI 1.6-4.4, p<0.001), a physical job (OR 1.8, 95%CI 1.1-3.1, p=0.03) and pulmonary arterial hypertension (OR 2.2, 95%CI 1.1-4.5, p=0.02) to be associated with unemployment. Unemployed patients had consistently poorer HRQoL scores in all domains (physical, emotional and mental health) of the SF-36 form than those who were employed.

CONCLUSIONS

SSc is associated with substantial work disability and unemployment, which is in turn associated with poor quality of life. Raising awareness, identifying modifiable risk factors and implementing employment strategies and work place modifications are possible ways of reducing this burden.

Mycophenolate mofetil is an effective and safe option for the management of systemic sclerosis-associated interstitial lung disease: results from the Australian Scleroderma Cohort Study

OBJECTIVES

To report the efficacy and tolerability of mycophenolate mofetil (MMF) and azathioprine (AZA) in the management of systemic sclerosis-associated interstitial lung disease (SSc-ILD).

METHODS

Patients in the Australian Scleroderma Cohort Study treated with at least 3 months of MMF or AZA for SSc-ILD confirmed on high resolution computed tomography (HRCT) chest were identified and their pulmonary function tests (PFTs) retrieved. Individuals with available results for T-1 (12 months prior to treatment commencement), T0 (date of treatment commencement) and at least one subsequent time point were included in the drug efficacy analysis. The Wilcoxon signed-rank test was used to compare absolute FVC at T1, T0, 12 months (T1), 24 months (T2) and 36 months (T3). Analysis of drug tolerability included all identified patients treated with MMF or AZA.

RESULTS

18/22 patients treated with MMF and 29/49 treated with AZA had adequate PFTs for inclusion in the drug efficacy analysis. Median absolute FVC at T1 for MMF treatment was 2.50L, declining to 2.12L at T0 (p=0.02). Following MMF therapy, FVC results were stable at T1 (2.13L, p=0.86), T2 (2.17L, p=0.65) and T3 (2.25L, p=0.78). In the AZA group, a statistically significant decline did not occur prior to treatment, however FVC results remained stable at T1, T2 and T3.Adverse events leading to early discontinuation (<12 months treatment) were less common in the MMF group (4/22 vs. 13/49). Gastrointestinal complications were the main cause of discontinuation in both groups.

CONCLUSIONS

In patients with SSc-ILD with declining pulmonary function, MMF therapy was associated with stability for up to 36 months. Early adverse events leading to discontinuation occurred less frequently in patients treated with MMF than in AZA treated patients.

The role of asymmetric dimethylarginine alone and in combination with N-terminal pro-B-type natriuretic peptide as a screening biomarker for systemic sclerosis-related pulmonary arterial hypertension: a case control study

OBJECTIVES

Asymmetric dimethylarginine (ADMA) is a novel biomarker of endothelial cell dysfunction. In this proof of concept study, we sought to evaluate the role of ADMA as a screening biomarker for incident systemic sclerosis-related pulmonary arterial hypertension (SSc-PAH).

METHODS

ADMA levels were measured using high performance liquid chromatography in 15 consecutive treatment-naive patients with newly-diagnosed SSc-PAH and compared with 30 SSc-controls without PAH. Logistic regression models were used to evaluate the independent association of ADMA with PAH. The optimal cut-point of ADMA for SSc-PAH screening was determined. NT-proBNP levels were previously measured in the same patients and the optimal cut-point of NT-proBNP of ≥210ng/mL was coupled with the optimal cut-point of ADMA to create a screening model that combined the two biomarkers.

RESULTS

The PAH group had significantly higher mean ADMA levels than the control group (0.76±0.14 μM versus 0.59±0.07 μM; p<0.0001). ADMA levels remained significantly associated with PAH after the adjustment for specific disease characteristics, cardiovascular risk factors and other SSc-related vascular complications (all p<0.01). An ADMA level ≥0.7 μM had a sensitivity of 86.7%, specificity of 90.0% and AUC of 0.86 for diagnosing PAH. A screening model that combined an NT-proBNP ≥210ng/mL and/ or ADMA ≥0.7 ng/mL resulted in a sensitivity of 100% and specificity of 90% for the detection of SSc-PAH.

CONCLUSIONS

In this small study, use of ADMA in combination with NT-proBNP produced excellent sensitivity and specificity for the non-invasive identification of SSc-PAH. The role of ADMA as a screening biomarker for SSc-PAH merits further evaluation.

A comparison of the predictive accuracy of three screening models for pulmonary arterial hypertension in systemic sclerosis

INTRODUCTION

There is evidence that early screening for pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc) improves outcomes. We compared the predictive accuracy of two recently published screening algorithms (DETECT 2013 and Australian Scleroderma Interest Group (ASIG) 2012) for SSc-associated PAH (SSc-PAH) with the commonly used European Society of Cardiology/European Respiratory Society (ESC/ERS 2009) guidelines.

METHODS

We included 73 consecutive SSc patients with suspected PAH undergoing right heart catheterization (RHC). The three screening models were applied to each patient. For each model, contingency table analysis was used to determine sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values for PAH. These properties were also evaluated in an 'alternate scenario analysis' in which the prevalence of PAH was set at 10%.

RESULTS

RHC revealed PAH in 27 (36.9%) patients. DETECT and ASIG algorithms performed equally in predicting PAH with sensitivity and NPV of 100%. The ESC/ERS guidelines had sensitivity of 96.3% and NPV of only 91%, missing one case of PAH; these guidelines could not be applied to three patients who had absent tricuspid regurgitant (TR) jet. The ASIG algorithm had the highest specificity (54.5%). With PAH prevalence set at 10%, the NPV of the models was unchanged, but the PPV dropped to less than 20%.

CONCLUSIONS

In this cohort, the DETECT and ASIG algorithms out-perform the ESC/ERS guidelines, detecting all patients with PAH. The ESC/ERS guidelines have limitations in the absence of a TR jet. Ultimately, the choice of SSc-PAH screening algorithm will also depend on cost and ease of application.