External Validation of a Septic Arthritis Prognosis Score

Study Overview
=================
Brief Summary
-----------------
Observational study

Detailed Description
-----------------
Septic arthritis is a diagnostic emergency for acute arthritis because it is accompanied by an excess of mortality of 11% and frequent functional sequelae in about 50% of cases in the year. However, it remains rare with an estimated annual incidence of 1 to 5/100000, and a prevalence of about 10% in front of an acute arthritis table sent to an emergency department. The diagnosis is based on the bacteriological culture which finds the presence of a microorganism within the joint. However, only 80% of septic arthritis is bacteriologically documented due to low inoculum, the presence of fragile bacteria (Neisseria sp) or especially untimely antibiotherapy prior to joint puncture. In addition, the bacteriological culture takes an average of 3 days to become positive, which may delay the implementation of appropriate antibiotic therapy. It is therefore essential that the clinician can rely on other clinical or biological parameters, reliable and fast for better diagnostic orientation. A first study: SYNOLACTATES showed the interest of the measurement of glucose and synovial lactate for the diagnosis of septic arthritis with very good performances. A RESAS score (REnnes Septic Arthritis Score) was constructed from these results to assess the likelihood of septic arthritis.

Official Title
-----------------
External Validation of the RESAS (REnnes Septic Arthritis Score) Septic Arthritis Prognosis Score in an Acute Arthritis Cohort of Less Than 30 Days

Conditions
-----------------
Arthritis

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Any acute arthritis less than or equal to 30 days; Achievement of a joint puncture in routine care as part of the diagnostic assessment of this acute arthritis; Affiliation to a social security scheme; No one opposes his participation in the research. Exclusion Criteria: Age below 18 years; Major persons subject to legal protection (safeguard of justice, guardianship, guardianship), persons deprived of their liberty.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| RESAS (Rennes Septic Arthritis Score) | Composite score of 4 biological variables of the synovial liquid (macroscopically purulent liquid and/or Synovial White Cells Counts (SWCC) ≥ 75000/mm3, synovial crystal vizualization, synovial lactate dosage, synovial glucose dosage). Each variable is weighted as follows: macroscopically purulent liquid or SWCC ≥ 75000/mm3 (+3 points), UMS (-4 points) or CPP (-2 points) crystal Vizualization, lactate ≥ 11.5 mmol/L (+6 points) or 10-11.4 mmol/L (+4 points) or 8.5-9.9 mmol/L (+2 points), glucose ≤ 1.0 mmol/L (+4 points), 1.1-1.8 mmol/L (+2 points), yielding a total between -4 and 13. | Up to 3 days (time to collect laboratory results) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Macroscopic synovial fluid appearance | Expressed in multiple qualitative variable: purulent, trouble, clear citrine appearance, hemarthrosis or clear with blood threads | Up to 1 day (time to collect clinical parameters) | 
| Microscopic synovial analysis | Presence of crystals in synovial fluid: urate monosodic (UMS) crystal (Yes or No), and calcium pyrophosphate crystal (CPP) (Yes or No) | Up to 3 days (time to collect laboratory results) | 
| Synovial White Cells Count (SWCC) | Number (n) of White cells in synovial fluid. (quantitative variable expressed in n/mm3) | Up to 3 days (time to collect laboratory results) | 
| Total lactates, D-lactate, glucose | Measures of total lactate, D-lactate et glucose in synovial fluid (quantitative variable expressed in mmol/L) | Up to 3 days (time to collect laboratory results) | 
| Others synovial proteic markers | Measures of CRP (mg/L) in synovial fluid | Up to 3 days (time to collect laboratory results) | 
| Others synovial proteic markers | Measures of Procalcitonine (ng/mL) in synovial fluid | Up to 3 days (time to collect laboratory results) | 
| Others synovial proteic markers | Measures of Calprotectin (ng/mL) in synovial fluid | Up to 3 days (time to collect laboratory results) | 
| Multielemental analysis by ICP-MS | Screening multielemental in synovial fluid | Up to 3 days (time to collect laboratory results) | 
| Number of classical clinical marker (quantitative variable) to diagnosis of septic arthritis | Fever (expressed in Celcius degree) | Up to 1 day (time to collect clinical parameters) | 
| Number of classical clinical marker (quantitative variable) to diagnosis of septic arthritis | Duration of symptoms (expressed in day) | Up to 1 day (time to collect clinical parameters) | 
| Number of classical clinical marker (qualitative variable) to diagnosis of septic arthritis | Co-morbidity promoting infection (diabetes, cirrhosis, HIV, severe chronic renal failure, rheumatoid arthritis, other inflammatory rheumatic diseases, immunosuppressive treatments such as corticosteroids, conventional synthetic-DMARDs, biological-DMARDs) (Yes or No) | Up to 1 day (time to collect clinical parameters) | 
| Number of classical clinical marker (qualitative variable) to diagnosis of septic arthritis | Number of joints affected (Ordinal variable) | Up to 1 day (time to collect clinical parameters) | 
| Parameters that may influence the bacteriological results of synovial fluid | NSAIDs, corticosteroids, antibiotics within 15 days of joint puncture (qualitative variable: Yes or No) | Up to 1 day (time to collect clinical parameters) | 
| Number of hospitalization potentially avoided by the early elimination of an arthritis diagnosis and their cost, from the point of view of illness insurance |  | Date of hospitalization until 2 months of follow-up |