Recognition of pulmonary hypertension in the rheumatology community: lessons from a Quality Enhancement Research Initiative.

OBJECTIVES: The aim of this study was to utilise the Quality Enhancement Research Initiative in Systemic Sclerosis (QuERI-SSc) to measure and reduce a perceived gap in the diagnosis of pulmonary arterial hypertension (PAH) associated with systemic sclerosis (SSc). METHODS: Rheumatologists enrolled patients with SSc (aged ≥ 18 years) and provided data on a panel of diagnostic tests over 3 years. Pulmonary function testing, echocardiography, 6-minute walk distance, N-terminal pro-brain natriuretic peptide assays, high-resolution computed tomography of the lungs, and ventilation/perfusion scan plus right heart catheterisation (RHC; when appropriate) were emphasised. Exclusion criteria included previously documented PAH, interstitial lung disease, and SSc overlapping with other connective tissue disease. RESULTS: Participating rheumatologists enrolled 207 patients with SSc (90% female; 80% white), with a median age of 57 years and median disease duration of 5 years. A total of 82% of patients were classified as New York Heart Association functional class I and II; of these patients, 177 had an echocardiogram at enrolment and 191 at any time during the study. Of those who met study-specified criteria for RHC at enrolment, only 3 of 7 patients underwent RHC. CONCLUSIONS: The screening algorithm was successful in identifying patients with mild impairment. Although specific tools were recommended for screening PAH in patients with SSc, results indicate that significant diagnostic care gaps still exist in the general rheumatology community. Better understanding and adherence to guidelines could improve the care and, ideally, outcomes of these high-risk patients.

Patterns and predictors of change in outcome measures in clinical trials in scleroderma: an individual patient meta-analysis of 629 subjects with diffuse cutaneous systemic sclerosis.

OBJECTIVE: To examine the range and responsiveness to change of clinical outcome measures and study predictors of clinical response in patients with diffuse cutaneous systemic sclerosis (dcSSc) in the context of clinical trials. METHODS: Data were combined from 629 patients with dcSSc who participated in 7 multicenter clinical therapeutic trials. Trials used common outcome measures: modified Rodnan skin thickness score (MRSS), Health Assessment Questionnaire disability index (HAQ DI), patient's global assessment of disease activity, pulmonary function tests (forced vital capacity, diffusing capacity for carbon monoxide), hand span, and oral aperture. RESULTS: The combined database included 629 patients (82% women, mean ± SD age 46.5 ± 11.8 years, mean ± SD disease duration 19.4 ± 15.9 months). Outcomes tended to improve during trials for patients with more severe disease at study entry and to worsen for patients with less severe disease at entry. Disease duration was mildly negatively predictive of change in MRSS at 6 months (r = -0.27, P < 0.001), and substantial bidirectional variation in change in MRSS and HAQ DI score was seen across the spectrum of disease duration. Sixty-three percent of patients with "early" disease (disease duration <18 months) had a decline in MRSS, and 37% had an increase in MRSS. Eighty-one percent of patients with "late" disease (disease duration ≥ 18 months) had a decline in MRSS, and 19% had an increase in MRSS. Multivariate mixed models did not demonstrate that any baseline variables were strongly predictive of subsequent outcome. CONCLUSION: Among patients with dcSSc enrolled in clinical trials, standard outcome measures tend to improve in those with more severe disease at study entry and to worsen in those with less severe disease at entry. Overall, the MRSS improves during trials, while HAQ DI scores and lung function are mostly static. None of these variables, including disease duration, reliably identifies groups of subjects whose MRSS will predictably increase or decrease in the course of a clinical trial. These findings have important implications for clinical trial design in scleroderma.

Differences in presentation of younger and older systemic sclerosis patients in clinical trials.

OBJECTIVES: To compare the characteristics of younger and older subjects with diffuse cutaneous systemic sclerosis (SSc) entering clinical trials. METHODS: Subjects were participants in three randomised interventional trials that shared relative uniformity of demographics and disease characteristics. Only subjects with diffuse cutaneous systemic sclerosis were evaluated. To maximise possible differences, the lowest (age<38 years) and highest quartiles (age>53 years) were used, and a total of 264 diffuse cutaneous SSc (dcSSc) subjects were identified. For the comparison between the two age groups, generalised linear mixed or linear models with adjustment for population norms, demographics and medications were employed to assess differences attributable to subject age. RESULTS: After adjustment for population norms and study effects, differences in diastolic blood pressure, alkaline phosphatase, AST, and creatinine phosphokinase (CK) were found between the two age groups. After further adjustment for demographics, disease duration and medications, older SSc patients still had significantly higher alkaline phosphatase (11 U/L higher), and lower CK (76 U/L lower) than younger patients (p<0.003 for all). All other variables were not significantly different in the two age groups. CONCLUSIONS: Clinical baseline differences exist between younger and older patients with SSc. However, after adjustment for population norms and potential confounders, including medications, only differences in alkaline phosphatise (only 11U/L) and CK (76 U/L) remain. Overall, older patients with SSc in clinical trials seem to be more similar to younger patients than was previously thought.

Randomized, prospective, placebo-controlled trial of bosentan in interstitial lung disease secondary to systemic sclerosis.

OBJECTIVE: Endothelin is implicated as a participatory pathway in systemic sclerosis (SSc). We tested this hypothesis in a 12-month trial of bosentan, a nonselective endothelin receptor antagonist, as a therapy for SSc-related interstitial lung disease (ILD). METHOD: Patients with SSc and significant ILD were recruited to this prospective, double-blind, randomized, placebo-controlled, parallel group study. The inclusion criteria were designed to select a cohort enriched for patients with active and progressive disease. Exclusion factors included significant pulmonary hypertension. Patients with a diffusing capacity for carbon monoxide of <80% predicted and a 6-minute walk distance of 150-500 meters or a 6-minute walk distance of > or = 500 meters with a decrease in oxygen saturation received bosentan or placebo. The primary efficacy end point was a change in the 6-minute walk distance from baseline up to month 12. Secondary end points included time to death or worsening results of pulmonary function tests (PFTs). The safety and tolerability of bosentan were also assessed. RESULTS: Among the 163 patients, 77 were randomized to receive bosentan, and 86 were randomized to receive placebo. No significant difference between treatment groups was observed for change in the 6-minute walk distance up to month 12. No deaths occurred in this study group. Forced vital capacity and diffusing capacity for carbon monoxide remained stable in the majority of patients in both groups. Significant worsening of PFT results occurred in 25.6% of patients receiving placebo and 22.5% of those receiving bosentan (P not significant). CONCLUSION: No improvement in exercise capacity was observed in the bosentan-treated group compared with the placebo group, and no significant treatment effect was observed for the other end points. Although many outcome variables were stable, bosentan did not reduce the frequency of clinically important worsening. These data do not support the use of endothelin receptor antagonists as therapy for ILD secondary to SSc.

Junctional adhesion molecule-A is abnormally expressed in diffuse cutaneous systemic sclerosis skin and mediates myeloid cell adhesion.

OBJECTIVE: To investigate the role of junctional adhesion molecule-A (JAM-A) in the pathogenesis of systemic sclerosis (SSc). METHODS: Biopsy specimens from proximal and distal arm skin and serum were obtained from patients with SSc and normal volunteers. To determine the expression of JAM-A on SSc dermal fibroblasts and in SSc skin, cell surface ELISAs and immunohistology were performed. An ELISA was designed to determine the amount of soluble JAM-A (sJAM-A) in serum. Myeloid U937 cell-SSc dermal fibroblast and skin adhesion assays were performed to determine the role of JAM-A in myeloid cell adhesion. RESULTS: The stratum granulosum and dermal endothelial cells (ECs) from distal arm SSc skin exhibited significantly decreased expression of JAM-A in comparison with normal volunteers. However, sJAM-A was increased in the serum of patients with SSc compared with normal volunteers. Conversely, JAM-A was increased on the surface of SSc compared with normal dermal fibroblasts. JAM-A accounted for a significant portion of U937 binding to SSc dermal fibroblasts. In addition, JAM-A contributed to U937 adhesion to both distal and proximal SSc skin. CONCLUSIONS: JAM-A expression is dysregulated in SSc skin. Decreased expression of JAM-A on SSc ECs may result in a reduced response to proangiogenic basic fibroblast growth factor. Increased JAM-A expression on SSc fibroblasts may serve to retain myeloid cells, which in turn secrete angiogenic factors.

Sexual activity and functioning in female scleroderma patients.

OBJECTIVE: Few studies exist on sexual activity and functioning in female patients with systemic sclerosis (SSc, scleroderma). We studied the patient-reported impact of SSc on sexual functioning among female patients. METHODS: 101 SSc patients completed the Short Form-36 (SF-36), the Female Sexual Functioning Index (FSFI) and the Female Sexual Function in Scleroderma (FSFS) questionnaires. RESULTS: Sixty patients reported being sexually active (59.4%). Reasons for sexual inactivity included lack of a partner (36.6%), personal choice (31.7%), and health status of the respondent's partner (19.5%). Only 7 subjects (17%) listed scleroderma as the primary reason for sexual inactivity. The mean FSFI score in the sexually active population was 24.9 (SD=6.7, range = 4.5-34.8) which is significantly lower than the mean score of 30.5 reported for the general population. Sexual functioning was significantly correlated with the Mental Component Score of the SF-36 (r=0.54, p<0.001) but surprisingly not with the Physical Component Score of the SF-36, age, and disease classification or duration. Several scleroderma-related problems including fatigue, body pain, vaginal dryness, and vaginal discomfort were cited as contributing to sexual difficulties. CONCLUSION: Women with scleroderma do remain sexually active overall in spite of several disease-related physical and psychological difficulties. Many of their problems are amenable to health interventions and should be addressed during health care visits.

Digital ulcers and outcomes assessment in scleroderma.

Ischaemic ulcerations of the fingertips are common in SSc and a source of pain and disability. Healing has been demonstrated with intravenous iloprost and two studies with bosentan have demonstrated reduction in the occurrence of new digital ulcers (DUs) over 4-6 months of treatment. Both bosentan studies showed no benefit in healing DU and because of this, net DU burden is no different between drug and placebo and accordingly secondary measures of outcome including pain and hand functionality are inconsistently affected. While it is likely an artefact, it remains unclear that current outcome measures including the Scleroderma Health Assessment Questionnaire (SHAQ), the UK Functional Score and the Michigan Hand Questionnaire are sensitive to change in the domain of digital ischaemia. Major events including amputation and hospitalization occur too infrequently to serve as practical measures of outcome in trials. Future studies of DU therapies will benefit from development of an ulcer-specific measure of outcome.

Trial design: how must we move ahead?

Scleroderma is clinically heterogeneous and a variety of plausible mechanisms of disease have been hypothesized. Recent years have witnessed a significant improvement in overall survival although all of the gains in management have been therapies for specific organ involvement, e.g. renal crisis and pulmonary arterial hypertension. Future studies will rely on improved clinical science, which involves structured validation of proposed measures of outcome; development of a combined response index; and further refinement of specific subsets of disease expression. Immunoablation with stem cell reconstitution is an example of aggressive therapy chosen as appropriate for a particularly severe disease subset and in whom the pilot data are encouraging. Good science and clinical ethics force continued consideration of equipoise between risk and benefit.

The 6-minute walk test in scleroderma--how measuring everything measures nothing.

The 6-min walk test (6MWT) is a standardized measure of submaximal exercise capacity that has served as the primary measure of outcome in studies of pulmonary arterial hypertension. Never fully validated in scleroderma, a variety of data suggest that many non-pulmonary aspects of scleroderma contribute to its results thereby blunting the ability of the 6MWT to measure change in lung function. Although reproducible, the lack of correlation with measures of parenchymal lung disease demonstrates an insurmountable lack of both construct and content validity. The 6MWT should be abandoned as an outcome measure in lung disease complicating scleroderma.

Development of a provisional core set of response measures for clinical trials of systemic sclerosis.

OBJECTIVE: To develop a provisional core set of response measures for clinical trials of systemic sclerosis (SSc). METHODS: The Scleroderma Clinical Trials Consortium (SCTC) conducted a structured, 3-round Delphi exercise to reach consensus on a core set of measures for clinical trials of SSc. Round 1 asked the SCTC investigators to list items in 11 pre-defined domains (skin, musculoskeletal, cardiac, pulmonary, cardio-pulmonary, gastrointestinal, renal, Raynaud phenomenon and digital ulcers, health-related quality of life and function, global health, and biomarkers) for SSc clinical trials. Round 2 asked respondents to rate the importance of the chosen items and was followed by a meeting, during which the Steering Committee discussed the feasibility, reliability, redundancy and validity of the items. Round 3 sought to obtain broader consensus on the core set measures. Members also voted on items that had data on feasibility but lacked data on reliability and validity, but may still be useful research outcome measures for future trials. RESULTS: A total of 50 SCTC investigators participated in round 1, providing 212 unique items for the 11 domains. In all, 46 (92%) participants responded in round 2 and rated 177 items. The ratings of 177 items were reviewed by the Steering Committee and 31 items from the 11 domains were judged to be appropriate for inclusion in a 1-year multi-centre clinical trial. In total, 40 SCTC investigators completed round 3 and ranked 30 of 31 items as acceptable for inclusion in the core set. The Steering Committee also proposed 14 items for a research agenda. CONCLUSION: Using a Delphi exercise, we have developed a provisional core set of measures for assessment of disease activity and severity in clinical trials of SSc.

Submaximal exercise testing in the assessment of interstitial lung disease secondary to systemic sclerosis: reproducibility and correlations of the 6-min walk test.

BACKGROUND: The 6-min walk test (6MWT) is increasingly used as an outcome measure in interstitial lung disease (ILD). AIM: To evaluate the usefulness of the 6MWT in a cohort of patients with ILD secondary to systemic sclerosis (SSc) and to correlate with established physiological parameters. METHODS: 163 patients with SSc-ILD were recruited for a multicentre, randomised, double-blind clinical trial. Available data at protocol screening included repeated 6MWTs, pulmonary function testing with diffusing capacity, Doppler echocardiography and high-resolution computed tomography of the thorax. Borg Dyspnoea Index was evaluated before and after 6MWT. RESULTS: Mean (standard deviation (SD)) distance walked during walk test 1 was 396.6 (84.55) m compared with 399.5 (86.28) m at walk test 2. The within-subject, intertest correlation as determined by Pearson's correlation coefficient testing was 0.95 (p<0.001). However, only weak correlations of 6MWT with percentage forced vital capacity and the Borg Dyspnoea Index were observed, and no correlation was observed with percentage diffusing capacity. CONCLUSION: These data confirm the high reproducibility of the 6MWT in patients with SSc-ILD and therefore the validity of the test in this cohort. The lack of correlation of 6MWT with standard physiological parameters of ILD suggests a multifactorial basis for limited exercise capacity in patients with SSc and calls into question the utility of the 6MWT as a measure of outcome in future studies on SSc-ILD.

Minimally important difference in diffuse systemic sclerosis: results from the D-penicillamine study.

OBJECTIVE: To estimate minimally important differences (MIDs) in scores for the modified Rodnan Skin Score (mRSS) and Health Assessment Questionnaire-Disability Index (HAQ-DI) in a clinical trial on diffuse systemic sclerosis (SSc). PARTICIPANTS AND METHODS: 134 people participated in a 2-year, double-blind, randomised clinical trial comparing efficacy of low-dose and high-dose D-penicillamine in diffuse SSc. At 6, 12, 18 and 24 months, the investigator was asked to rate the change in the patient's health since entering the study: markedly worsened, moderately worsened, slightly worsened, unchanged, slightly improved, moderately improved or markedly improved. Patients who were rated as slightly improved were defined as the minimally changed subgroup and compared with patients rated as moderately or markedly improved. RESULTS: The MID estimates for the mRSS improvement ranged from 3.2 to 5.3 (0.40-0.66 effect size) and for the HAQ-DI from 0.10 to 0.14 (0.15-0.21 effect size). Patients who were rated to improve more than slightly were found to improve by 6.9-14.2 (0.86-1.77 effect size) on the mRSS and 0.21-0.55 (0.32-0.83 effect size) on the HAQ-DI score. CONCLUSION: MID estimates are provided for improvement in the mRSS and HAQ-DI scores, which can help in interpreting clinical trials on patients with SSc and be used for sample size calculation for future clinical trials on diffuse SSc.

Digital ulcers in systemic sclerosis: prevention by treatment with bosentan, an oral endothelin receptor antagonist.

OBJECTIVE: Recurrent digital ulcers are a manifestation of vascular disease in patients with systemic sclerosis (SSc; scleroderma) and lead to pain, impaired function, and tissue loss. We investigated whether treatment with the endothelin receptor antagonist, bosentan, decreased the development of new digital ulcers in patients with SSc. METHODS: This was a randomized, prospective, placebo-controlled, double-blind study of 122 patients at 17 centers in Europe and North America, evaluating the effect of treatment on prevention of digital ulcers. The primary outcome variable was the number of new digital ulcers developing during the 16-week study period. Secondary assessments included healing of existing digital ulcers and evaluation of hand function using the Scleroderma Health Assessment Questionnaire. RESULTS: Patients receiving bosentan had a 48% reduction in the mean number of new ulcers during the treatment period (1.4 versus 2.7 new ulcers; P = 0.0083). Patients who had digital ulcers at the time of entry in the study were at higher risk for the development of new ulcers; in this subgroup the mean number of new ulcers was reduced from 3.6 to 1.8 (P = 0.0075). In patients receiving bosentan, a statistically significant improvement in hand function was observed. There was no difference between treatment groups in the healing of existing ulcers. Serum transaminase levels were elevated to >3-fold the upper limit of normal in bosentan-treated patients; this elevation is comparable with that observed in previous studies of this agent. Other side effects were similar in the 2 treatment groups. CONCLUSION: Endothelins may play an important role in the pathogenesis of vascular disease in patients with SSc. Treatment with the endothelin receptor antagonist bosentan may be effective in preventing new digital ulcers and improving hand function in patients with SSc.

Assessment of skin, joint, tendon and muscle involvement.

This report makes recommendations for standardized techniques of data gathering and collection regarding: 1) skin involvement 2) joint and tendon involvement, and 3) involvement of the skeletal muscles. The recommendations in this report derive from a critical review of the available literature and group discussion. Committee recommendations are considered appropriate for descriptive clinical investigation, translational studies and as standards for clinical practice. Skin involvement should be assessed using the modified Rodnan skin score. Joint involvement, when symmetric synovitis is present, could be best assessed by the DAS-28 as is utilized in rheumatoid arthritis. Clinical assessment should include a routinized evaluation for the presence and number of palpable tendon friction rubs. Muscle involvement should be screened for by performance of the serum creatine phosphokinase assay and assessment of proximal weakness. More specific testing including EMG, magnetic resonance imaging and muscle biopsy should be employed in those patients with clinically significant myopathy only.

Clinical trials: types, design, and end-points.

Although the pathogenesis of systemic sclerosis is poorly understood, an increasing number of high quality clinical research trials are attempting to modify the overall disease outcome. Survival has improved, largely through therapies focused on single organs. Candidate outcome measures have been tested and a consensus template for trial design has evolved. The complexity of process in systemic sclerosis renders unlikely that an agent of focused mechanism of therapeutic effect will alter all cardinal features of illness.

Effects of the American College of Rheumatology systemic sclerosis trial guidelines on the nature of systemic sclerosis patients entering a clinical trial.

OBJECTIVES: To compare the systemic sclerosis (SSc) patients entered into the d-penicillamine trial with SSc patients entered into previous controlled SSc trials. It was hypothesized that the d-penicillamine trial patients, who conformed to the American College of Rheumatology (ACR) guidelines for clinical trials in SSc were different from patients entered into previous trials. METHODS: Patients entering a double-blind, randomized trial of low- vs high-dose d-penicillamine were described carefully and completely. Their characteristics were then compared with previously published data on SSc and its treatment. RESULTS: One hundred and thirty-four patients had early [mean duration 9.5 (s.d. 4.2) months], diffuse [skin score 21 (8)] disease. Organ involvement in the patients was as follows: pulmonary 54%, cardiac 20%, joints 38%, muscular 20%. Thirty-three per cent had mild proteinuria and 13% were hypertensive when first seen. Compared with patients in most previous studies, these SSc patients had earlier disease and uniformly had diffuse disease. They had less muscular involvement, less dyspnoea, less abnormal pulmonary function and less cardiac and less renal involvement than patients in earlier studies. CONCLUSIONS: The use of the new ACR guidelines for SSc trials may change the nature of patient populations entering future studies.

A randomized, controlled trial of methotrexate versus placebo in early diffuse scleroderma.

OBJECTIVE: Early diffuse scleroderma (systemic sclerosis; SSc) has no proven treatment. This study was undertaken to examine the efficacy of methotrexate (MTX) in improving the skin and other disease parameters in early diffuse SSc. METHODS: Seventy-one patients with diffuse SSc of <3 years' duration were enrolled in a multicenter, randomized, placebo-controlled, double-blind trial. Thirty-five patients were treated with MTX and 36 with placebo. Treatment was administered for 12 months. The primary outcome measures were skin score (as determined with 2 different indices) and physician global assessment. RESULTS: At baseline, there were no statistically significant differences in skin scores, carbon monoxide diffusing capacity (DLco), physician global assessment, or other secondary outcome measurements between the 2 treatment groups. At study completion, results slightly favored the MTX group (mean +/- SEM modified Rodnan skin score 21.4+/-2.8 in the MTX group versus 26.3+/-2.1 in the placebo group [P < 0.17]; UCLA skin score 8.8+/-1.2 in the MTX group versus 11.0+/-0.9 in the placebo group [P < 0.15]; DLco in the MTX group 75.7+/-4.6 versus 61.8+/-3.4 in the placebo group [P < 0.2]). In addition, physician global assessment results favored MTX (P < 0.035), whereas patient global assessment did not differ significantly between groups. When between-group differences for changes in scores from baseline to 12 months were examined using intent-to-treat methodology, MTX appeared to have a favorable effect on skin scores (modified Rodnan score -4.3 in the MTX group versus 1.8 in the placebo group [P < 0.009]; UCLA score -1.2 in the MTX group versus 1.2 in the placebo group [P < 0.02]), but differences in the degree of change in the DLco and physician global assessment were not significant. For the UCLA skin score, these differences in results were not statistically significant after adjustment for baseline differences in sex distribution and steroid use. Dropout rates were similar in the 2 groups. CONCLUSION: Although results of this trial demonstrated a trend in favor of MTX versus placebo in the treatment of early diffuse SSc, the between-group differences were small and the power to rule out false-negative results was only 50%. Our findings do not provide evidence that MTX is significantly effective in the treatment of early diffuse SSc.

The Disability Index of the Health Assessment Questionnaire is a predictor and correlate of outcome in the high-dose versus low-dose penicillamine in systemic sclerosis trial.

OBJECTIVE: To explore the clinical implications of a score of > or =1.0 on the Disability Index of the Health Assessment Questionnaire (HAQ DI) at the first patient visit, and to examine the implications of improvement in HAQ DI score over 2 years in a cohort of systemic sclerosis (SSc) patients with diffuse cutaneous scleroderma. METHODS: SSc skin and visceral involvement was assessed in 134 SSc patients with diffuse scleroderma (mean +/- SD disease duration of 10 +/- 4 months) when they entered a multicenter drug trial and again 2 years later. Mortality and the occurrence of scleroderma renal crisis were assessed for a mean +/- SD of 4.0 +/- 1.1 years. Logistic and linear regression analyses were used to examine the relationship of the baseline HAQ DI score to morbidity, mortality, and visceral involvement, as well as the relationship of changes in the HAQ DI score to changes in physical examination, laboratory, and functional variables over 2 years. RESULTS: A baseline HAQ DI score of > or =1.0 was predictive of mortality (odds ratio 3.22, 95% confidence interval 1.097-9.468) over 4 years. Multivariate linear regression demonstrated that a model which included the erythrocyte sedimentation rate at baseline (P = 0.005) and changes at 2 years in the swollen joint count (P = 0.002), total skin score (P = 0.005), and white blood cell count (P = 0.005) best explained the change in HAQ DI score over 2 years (R2 = 0.528). The HAQ DI score and total skin score at baseline were highly correlated (correlation coefficient 0.368), as were changes in the HAQ DI score and the total skin score over 2 years (correlation coefficient 0.492). Although the HAQ DI score was heavily influenced by hand dysfunction at baseline and at 2 years, improvement (reduction) in the HAQ DI score over 2 years was related to factors other than hand dysfunction. CONCLUSION: A baseline HAQ DI score of > or =1.0 predicted mortality over 4 years. Improvement in the HAQ DI score in these patients with diffuse scleroderma was associated with improvement in skin thickening, hand function, oral aperture, lung function, signs of arthritis, serum creatinine level, and the investigator's global assessment of improvement. The HAQ DI is a self-administered questionnaire that SSc patients can complete easily and rapidly and that gives the practicing physician important information about prognosis, patient status, and changes in disease course over time.