Here is the design of a clinical trial:

Official Title: Ultrasound in PSoriatic Arthritis TREAtMent - UPSTREAM

Included conditions:
- Arthritis, Psoriatic
- Ultrasonography
- Minimal Disease, Residual

Study Armgroups:
- {'label': 'Patients with active Psoriatic Arthritis', 'description': 'Patients with clinically diagnosed PsA with clinically active joint disease starting a new course of treatment.', 'interventionNames': ['Drug: New course of treatment']}

Interventions:
- {'type': 'DRUG', 'name': 'New course of treatment', 'description': 'Prescription of new course of NSAIDs (monotherapy), steroid intra-articular injections (monotherapy), conventional DMARDs, biologic DMARDs, including switches or dose augmentations, indicated by the treating rheumatologist according to usual clinical practice.', 'armGroupLabels': ['Patients with active Psoriatic Arthritis'], 'otherNames': ['NSAIDs', 'steroid intra-articular injections', 'Conventional DMARDs', 'biologic DMARDs']}

Primary Outcomes:
- {'measure': 'Minimal disease activity', 'description': 'The Minimal disease activity (MDA) calculation will be based on the evaluation of 7 variables:\n\n1. 68 tender joints count (≤1)\n2. 66 swollen joint count (≤1)\n3. Body Surface Area (BSA) ≤3\n4. Patient pain VAS (≤15 mm);\n5. Patient global disease activity VAS (≤20 mm);\n6. HAQ (≤0.5);\n7. Leeds Enthesitis Index (LEI) tender entheseal points (≤1) Patients will be classified as having MDA if they meet 5 out of these 7 criteria (value in brackets).', 'timeFrame': '6 months'}

Please estimate the sample size based on the assumption: 
The simulations used the Stata procedure rocsize, aiming for over 90% power with a 5% significance level. The percentage of diseased subjects was assumed to be 60%. A maximum attrition rate of 20% was considered.
Sample size calculation
        The sample size calculation was done minimising the number of false positives (ie, the number of false non-responsive to treatment) in order to minimise the risk of overtreating patients who actually have a good response to therapy. Therefore, sample size was calculated to minimise this risk by 40% (null hypothesis H0) to 20% (alternative hypothesis H1), maintaining stable at 70% (both for the H0 for both the H1), the percentage of true positives (true unresponsive to therapy).
        The simulations were carried out using the Stata procedure rocsize (by M. Pepe), which allows to determine the power to detect an improvement in theÂ receiver operating characteristic (ROC) curve. The procedure requires that the percentage of false and true positives are specified for both the null and the alternative hypothesis and also the percentage of diseased.
        Using the command rocsize 0.7 0.2, na (150) ndb (100) tpnull (0.7) fpnull (0.4) of Stata, it results that 250 patients are sufficient to evaluate the performance of a model (and its ROC curve) with over 90% of power (setting a 5% alpha). Specifically, we have assumed a 70% and a 20% of subjects true positives and false positives, respectively, according to the alternative hypothesis, a 70% and a 40% of subjects true positives and false positives, respectively, according to the null hypothesis, and a percentage of diseased of 60% (150 of 250 subjects).
        Under the assumption of maximum attrition of 20%, the sample size will be increased to 300 patients. The same sample size is sufficient to precisely estimate a logistic model of achievement of an MDA (probability of 0.4 at 6 months) with 10 predictors (rule of thumbs).
        Based on the prestudy activities, 40 investigators will be involved, 15 from tertiary and 20â25 from secondary rheumatology centres. Enrolment will last 12 months at each participating centre; assuming four eligible patients per month for tertiary and one per month in secondary centres and a 40% enrolment rate, about 30 patients per month are expected.