Introduction Osteoarthritis is a chronic disease characterized by a progressive degradation of articular cartilage. Hand OA involves symptomatically more than 1 million of subjects in France (i.e., painful or with functional impairment). To date, the treatment of OA is only symptomatic and no drugs are able to stop the degradative process of cartilage.

50% of patients with hand OA exhibit a functional impairment responsible for a severe handicap, which is almost similar to rheumatoid arthritis. While the risk factors of hand OA are well identified (i.e., familial history, female sex, menopause, obesity), clinical outcome in large cohort is poorly known. In addition, the investigators miss predictive clinical, biological or imaging factors of severe clinical (i.e. pain, functional impairment or aesthetic damage) or structural evolution (i.e., aggravation of radiographic scores).

Primary objective To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation after 6 years of follow-up.

Secondary objectives To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation after 3 years of follow-up.

To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation after 3 years of follow-up.

To investigate whether variations of clinical evaluation of hand hand OA and radiographic structural changes are associated or correlated between inclusion and 3 years of follow-up or between inclusion and 6 years follow-up To investigate whether clinical status and radiographic alterations are correlated at inclusion To determine whether hand OA is associated with OA at other sites or with other hand diseases (carpal tunnel syndrome, tendinitis) To evaluate frequency of erosive hand OA among the whole hand OA cohort at inclusion, at 3 and 6 years of follow-up To identify clinical, biological, genetic and imaging factors associated with erosive hand OA (versus non erosive hand OA) at inclusion or during the follow up (3 and 6 years) To investigate predictive clinical, biological, genetic and imaging factors of clinical or radiographic aggravation after 3 or 6 years of follow-up in the erosive hand OA subgroup

Methods :

the investigators plan to include 500 patients in the cohort (5/week) 7 visits (one per year) are planned: M0, M12, M24, M36, M48, M60 and M72. A clinical evaluation of hand OA will be performed at each visit. At visit M0, M36 and M72, hand radiographs and radiographs of other OA localisation (if symptomatic) will be performed.

A blood sample will be taken at inclusion for biomarker studies and genetic investigations.

A blood sample will be taken at M36 and M72 to build a prospective serum collection.

Duration of the study: 8.5 years with 2.5 years of inclusion period Duration of the study for one patient: 6 years Recruitment at the Rheumatology Department of Saint-Antoine Hospital with a multicentric international steering committee

Potential outcomes :

• Identification of clinical, radiological and biological tools useful to predict clinical and structural outcomes
• Description of the history course of hand OA and predictive factors of severe evolution (i.e. erosive form of hand OA) To integrate in daily practice, clinical and radiological tools allowing a standardized follow up of hand OA patients.

Primary objective To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation after 6 years of follow-up.

Secondary objectives To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation after 3 years of follow-up.

To investigate in hand OA patients predictive clinical, biological, genetic and imaging factors of clinical aggravation between inclusion and 3 years of follow-up and between inclusion and the end of follow-up at 6 years.

To determine the clinical, biological and radiographic factors predictive of the radiographic progression of OA between inclusion and 3 years but also between inclusion and 6 years To investigate whether clinical changes and radiographic structural changes are associated or correlated between inclusion and 3 years of follow-up or between inclusion and 6 years of follow-up To investigate whether clinical status and radiographic alterations are correlated at inclusion To determine whether hand OA is associated with other OA at other sites or with other hand diseases (carpal tunnel syndrome, tendinitis) To evaluate frequency of erosive hand OA among the whole hand OA cohort at inclusion, at 3 and 6 years of follow-up To identify clinical, biological, genetic and imaging factors associated with erosive hand OA (versus non erosive hand OA) at inclusion or during the follow up (3 and 6 years) To investigate predictive clinical, biological, genetic and imaging factors of clinical or radiographic aggravation after 3 or 6 years of follow-up in the erosive hand OA subgroup To perform a cross-sectional analysis of the correlation between clinical tools and erosive radiographic involvement at inclusion (in the population with erosive hand OA at inclusion) ; To evaluate the frequency of fibromyalgia at 3 years of follow-up and at the end of the follow-up at 6 years ; To evaluate the frequency of neuropathic pain at 3 years of follow-up and at the end of the follow-up at 6 years ; To evaluate the pressure pain threshold at 3 years of follow-up and at the end of the follow-up at 6 years.

Methods : Prospective observational study The study will be proposed to all patients viewed at the out-patient clinic for hand OA which took place in Saint-Antoine Hospital in Rheumatology Department since 2004 (usually 12/week). The investigators plan to include 500 patients in the cohort (5/week).

7 visits (one per year) are planned: M0, M12, M24, M36, M48, M60 and M72. A clinical evaluation of hand OA will be performed at each visit. At visit M0, M36 and M72, hand radiographs and radiographs of other OA localisation (if symptomatic) will be performed.

A blood sample will be taken at inclusion for biomarker studies and genetic investigations.

A blood sample will be taken at M36 and M72 to build a prospective serum collection.

Duration of the study: 8.5 years with 2.5 years of inclusion period Duration of the study for one patient: 6 years Recruitment at the Rheumatology Department of Saint-Antoine Hospital with a multicentric international steering committee

Inclusion Criteria:

• Patients above 35-years old, having hand OA according to one of the following definitions:
• symptomatic hand OA fulfilling ACR criteria on at least 2 joints among proximal interphalangeal, distal interphalangeal joints or 1st interphalangeal joint with Kellgren-Lawrence > 2
• symptomatic thumb base OA with Kellgren-Lawrence > 2

Exclusion Criteria:

• Inflammatory rheumatic destructive disorders (psoriatic arthritis, rheumatoid arthritis)
• Polyarthritis related to gout or chondrocalcinosis involving hand
• Secondary hand OA related to infection or traumatism
• Secondary OA related to genetic dysplasia
• Pregnancy and feeding