Economic background can have an impact on patient-reported outcomes

There are differences in outcomes across countries, with worse physician-reported outcomes but better patient reported outcomes in low-income countries.

Rheumatoid arthritis is a chronic inflammatory disease that affects a person’s joints, causing pain and disability. It can also affect internal organs. Rheumatoid arthritis is more common in older people, but there is also a high prevalence in young adults, adolescents and even children, and it affects both men and women. Inequalities in the health of people with rheumatoid arthritis have been reported. Previous studies have noticed that rheumatoid arthritis patients with lower incomes or lower levels of education have higher disease activity than those who are wealthier or have completed higher education. This link also seem to be true at international level, as people in less wealthy countries tend to have worse disease activity than people living in richer countries.

The authors aimed to investigate the patterns in health outcomes reported by doctors and their patients with rheumatoid arthritis, and to see whether there was a difference between countries with different level of socioeconomic development. The authors were also interested in looking at specific outcomes such as fatigue, which in some countries is not considered to be a problem related to the disease.

The study included 3,920 patients from around the world. People attending outpatient rheumatology clinics were invited to join the study if they were over 18 years old, fulfilled the 1987 American College of Rheumatology classification criteria for rheumatoid arthritis, and were able to understand and complete the questionnaires.

This was a cross-sectional, observational study called COMOrbidities in Rheumatoid Arthritis (COMORA), which collected information about people with rheumatoid arthritis in 17 countries. The authors made no interventions and there was no medicine under investigation in this study – they simply asked people to complete questionnaires about their disease at a specific point in time. The questionnaires collected information on tender and swollen joints and disease activity, as well as laboratory assessments of markers of inflammation in the blood (called CRP and ESR), quality of life and tiredness. Countries were classed as being either wealthy or poor on the basis of their GDP (gross domestic product). GDP is a measure of the value of goods and services that a country produces every year. These values are used to work out the economic performance, which can then be used to make comparisons. Richer countries have a higher GDP than poorer ones.

The authors found important differences between people in the poor and wealthy countries. People with rheumatoid arthritis in poorer countries reported feeling better, despite having high disease activity. People living in richer countries reported feeling more tired and unwell, even when they had low disease activity and better function or ability. These differences remained even after taking into account people’s sex, level of education and any other diseases (comorbidities) they might have.

Yes. This is the first time that a paradox in outcomes for people with rheumatoid arthritis has been described.

There are some limitations to studies like COMORA, because they cannot guarantee that they include a representative sample of the people with rheumatoid arthritis in each of the participating countries. Rheumatology clinics with specific research interests are more likely to sign up to be involved in these kinds of studies, which can skew the results. However, the authors are confident that this would probably lead to underestimation rather than overestimation of the observed effects. A common limitation for this type of study is the crosssectional design, which makes it difficult to draw conclusions about what might cause the observed differences.
Another limitation is the use of GDP as a marker of a country’s wealth. However, GDP is commonly used in international studies, and is considered to be a suitable measure of wealth for these purposes.

Explaining the results of this study is not straightforward, and future studies are needed to understand it. Future studies should consider looking at cultural differences. It is possible that in richer countries, people with rheumatoid arthritis might have better access to good treatments. However, this may lead to overoptimistic expectations about the treatment, and make patients believe that it should dramatically improve all aspects of their disease. In wealthier societies people may also experience higher pressure in terms of performing many social roles (family, work, social life) and therefore feel less satisfied with their health state. These factors could explain why patients have low disease activity but at the same time report feeling worse compared to their counterparts in poorer countries. It is of note that some medicines can cause fatigue, but even when accounting for differences in treatment, the observation remained unaltered.

If you have rheumatoid arthritis, it is important to understand that the lifestyle choices you make are important – no matter where in the world you live. There are some steps you can take to make sure you stay healthy and feel better. These can include being careful about your diet, and taking exercise to help keep your joints mobile. If you find your disease limits your activities, try to adapt your life to your physical abilities, since this will give you more control. If you are receiving treatment for your rheumatoid arthritis, you should talk to your doctor to set realistic goals and expectations. You may also find it helpful to consult health specialists such as a chiropodist, psychologist or physiotherapist.

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Date prepared: April 2016

Summary based on research article published on: 27 August 2015

From: Putrik, P. et al. In wealthier countries, patients perceive worse impact of the disease although they have lower objectively assessed disease activity: results from the cross-sectional COMORA study. Ann Rheum Dis 2016;75:751–20. doi:10.1136/annrheumdis-2015-207738

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