Hand, hip and knee osteoarthritis in a Norwegian population-based study - The MUST protocol

While late-stage OA is often characterised by both demonstrable structural changes (loss of joint space, osteophytes and changes in the subchondral bone) and patient-reported joint pain, stiffness and disability, there are only weak correlations between symptoms and OA pathology, particularly in early stages of the disease[21]. It has been estimated that 40-80% of individuals with radiographic changes have concurrent symptomatic OA disease[14, 29]. The discrepancy between imaging and clinical findings is becoming more complex with increased use of sensitive imaging techniques such as magnetic resonance imaging (MRI), which more frequently demonstrates structural abnormalities, inflammatory changes, and degeneration of soft tissue compared to conventional radiographs[30]. Most studies using MRI have included patients with knee OA, showing that bone marrow lesions and synovitis are associated with pain[31]. Similar results have been found in hand OA[30, 32], although more studies are needed. Ultrasound also has the ability to demonstrate both changes in bone and soft tissue, and a scoring system for use in hand OA has been developed[33, 34], but further work to validate ultrasound features of OA is needed[35].

Recently, there has been an interest in classifying OA populations into different clinical and/or structural phenotypes, which might improve the understanding of the disease and allow the treatment to become more targeted and tailored. A proposal for differentiation of clinical phenotypes based on age and primary causative features has been published[15]. Further, cluster analyses using data from knee OA participants in the Osteoarthritis Initiative Study have been performed to identify phenotypes with different clinical outcomes[36]. More research on classifications of different phenotypes may further improve the development within diagnosis, treatment, and monitoring of the OA disease.

Hand photography is an easy and inexpensive imaging method involving no harm for the subjects. A standardised procedure for taking digital hand photographs, a set of reference photographs, and standardised reading procedure for diagnosing hand OA has been published showing adequate inter- and intraobserver variation[37]. However, the diagnostic value of hand photography in hand OA needs further investigation. The importance of measuring aesthetic damage in individuals with hand OA has been recognised[38, 39]. The extent to which deformities in affected joints may have a negative influence on individuals’ social life has not been systematically assessed. The relation between hand OA and hypermobility is scarcely investigated, and previous research has shown conflicting evidence[9]. More insight into this association would be interesting in order to provide preventive strategies. Obesity has been shown to be an important risk factor for OA, especially for knee OA[2] and for total hip replacement[40, 41], but there is now also increasing evidence suggesting a relationship between obesity and hand OA[9]. Whether OA is part of a “metabolic syndrome” including overweight, hypertension, and diabetes is being debated and needs further examination. Affection of the carpometacarpal joint in the thumb may compromise function in the whole hand, and was found to contribute more to pain and disability than affection of the interphalangeal joints[42]. More research on factors associated with OA in the carpometacarpal joint in the thumb is needed.

Recently, there has been substantial interest in the relationship between various arthritic disorders in relation to cardiovascular morbidity[43]. Some studies have shown an association between OA and cardiovascular morbidity and mortality[44], and it has been suggested that atherosclerosis may contribute to the initiation or progression of OA[45, 46]. An association between arterial stiffness and hand OA has been found, but the significant individual relationship was largely attributable to the confounding effect of age[43]. These findings and novel hypotheses need to be explored in longitudinal studies.

Several international recommendations and standards of care for OA management have been developed[2, 47‐51]. However, there has been limited focus on evaluation of the quality of care provided for OA patients, and previous studies have revealed low adherence with published recommendations[52‐54], and have suggested that OA care was suboptimal[55‐58]. An English study by Steel et al. showed that the pass rate for quality indicators on OA management was only 29%[59], and we expect that the situation in Norway is similar. The only Norwegian study in this area is a prospective study on physiotherapy performance in patients with knee OA, in which the authors concluded that there is a need to promote high quality evidence into physiotherapy practice[60].

In Sweden, it was reported that individuals with knee OA have close to twofold increased risk of sick leave and about 40-50% increased risk of disability pension compared to the general population[61]. It is unknown whether similar figures can be found in Norway. The costs of OA care will be heavily influenced by the trends in OA occurrence, the severity of the disease, and the consequences of OA in function and work ability. More research is warranted on utilisation of self-management and treatment in primary, secondary, or tertiary care.

At least 30 minutes physical activity per day for at least 3 days a week is recommended as a general guideline for those with knee and hip OA[62]. Knowledge on type and level of physical activity in individuals with OA is limited. A large survey conducted in the US indicated that those with OA were less active than healthy individuals[63], but the activity level according to affected joint was not investigated. A recent US study showed that only 13% of men and 8% of women with knee OA met the aerobic component of the 2008 Physical Activity Guidelines for Americans (≥150 minutes/week of moderate-to-vigorous–intensity activity lasting ≥10 minutes)[64]. A recent Norwegian study with accelerometer-determined physical activity revealed that only one in five adults or older people met the current national physical activity recommendations to accumulate at least 30 minutes of daily moderate intensity physical activity[65]. The study also showed that overweight and obese participants performed less overall physical activity compared to normal weight participants[66]. However, knowledge of physical activity levels in Norwegian individuals with OA is needed.

This study has been designed to recruit individuals from an unselected adult population to gain more knowledge about clinically and radiologically confirmed OA, risk factors, consequences, and management of OA. The study incorporates different imaging techniques (conventional radiographs, MRI, and US), patient-reported outcomes and performance-based outcome measures, cardiovascular morbidity and metabolic syndrome in individuals with hand, hip and/or knee OA. Such data will be valuable for various epidemiological and clinical studies.

The main aims of the present study are to evaluate:

The MUST has been designed as an observational study which includes a population-based postal survey (Q1) as well as a subsample (the MUST OA cohort) who attend a comprehensive clinical examination (CE) and complete OA specific questionnaires (Q2 and Q3).

The target population for the postal population-based survey is the inhabitants in the Ullensaker Municipality, which is a rural community 40 kilometres northeast of Oslo. Some of the nearly 30 000 inhabitants commute to Oslo for work, but for the last 10 to 15 years, the work opportunities and the number of Ullensaker inhabitants have expanded due to the building and the subsequent management related to the national Oslo Airport Gardermoen. This development has resulted in some minor changes in demographic factors, as many persons of younger age and with higher education levels have moved into the municipality.

All inhabitants aged between 40 and 79 years receive the postal four page questionnaire (Q1). Information on residence is provided by the Population Register. The questionnaire is returned by mail in a pre-paid envelope. One written reminder is sent to non-responders after eight weeks.

Individuals eligible for the comprehensive clinical examination are identified using the self-reported OA item in the population-based postal survey (Q1): ‘Have you ever been diagnosed with osteoarthritis in hip/knee/hand by a medical doctor and/or x-ray?’ Response categories include: Yes, hip/ Yes, knee/ Yes, hand/ No. Those who self-report OA in their hip, knee, and/or hand, will receive a postal request to attend a clinical examination (CE) performed at Diakonhjemmet Hospital, Oslo. Two written reminders are sent to non-responders. The participants are screened for clinical examination eligibility by the project coordinator, and those who are unable to walk (with or without walking aids) and/or do not speak or understand Norwegian language are excluded for the clinical examination.