Cystic Fibrosis-Related Arthritis: Who, What, Why, and How?

Do you or a loved one have cystic fibrosis?  CF is known for its severe pulmonary issues.  Recent new chloride channel upregulation (Trikafta) has radically altered lives and increased life spans to near normal.

As patients mature they will exhibit diseases such as arthritis. Many will also grapple with CF-related diabetes.

How little we know about CFA and its treatment. There’s a substantial lack of research on CFA because of the complexity of this complication, although it significantly affects quality of life. Here’s the who, what, why, and how according to the current research and the holes in information that need to be filled to better manage CFA.

Who has cystic fibrosis-related arthritis?

According to the Cystic Fibrosis Patient Registry from 2018, six percent of the population reported cystic fibrosis-related arthritis as a complication of CF.1 In another report, CFA had an estimated prevalence rate of 2% to 8.5%, but is thought to increase as people with CF live longer.2

Although both children and adults can experience CFA, the average age of onset is around 13.6 years and 17 years, respectively.3,4 What I found most interesting was the occurrence of CFA didn't differ based on pulmonary function, sputum cultures, or gastrointestinal symptoms.2

What is cystic fibrosis-related arthritis?

Unfortunately, there is no formal definition of CFA other than recurrent episodes of joint pain, swelling, tenderness, stiffness, and limited mobility sometimes in conjunction with fever or rashes.2 The large joints such as knees, wrists, elbows, and shoulders are the most common joints affected. Often, the pain is not symmetric across joints and can affect different sets of joints with each episode.2

Generally, episodes of CFA can last for up to a week or occur chronically without symptoms resolving completely.2 More often a “remitting and relapsing” course occurs where symptoms get worse and then get better until the next attack. Even with persistent disease, patients often don’t meet the criteria to be diagnosed with rheumatoid arthritis. Results are often normal during X-rays of the affected joints. The vague collection of symptoms makes it especially hard to diagnose and treat CFA, especially because each patient’s experience is different.

Why does CF-related arthritis happen?

The mechanism of CFA is not fully understood or known. A couple theories exist that could explain why CFA happens in people living with CF. The hyperactive immune response from chronic lung infections and inflammation is thought to be the reactive source of joint pain.4 Moreover, because there’s persistent infection and, therefore, inflammation, the immune system works overtime causing an inflammatory reaction within the joints. Makes sense to me! However, no specific antigen in the immune response has been identified.

Another theory is that some people with CF are genetically predisposed to develop CFA.4 Just as salty skin, clubbing, or occasional pancreatic sufficiency are physical traits of CF, or genetic phenotypes, some researchers believe inflammatory arthritis is another phenotype that can be expressed in the disease. However, there’s been no further research studying CFTR genotypes and CFA.

The last theory explaining CFA is connected to gastroenterology complications of CF such as malabsorption and other GI issues. Many other arthritic syndromes are connected to GI diseases such as inflammatory bowel disease, entheogenic reactive arthritis (arthritis caused by an infection in the intestines), and arthritis of intestinal bypass surgery.4 All varieties have similar characteristics as CFA and could give a possible explanation to a link in CF.

Bottom line: there needs to be more research.

Cystic Fibrosis-Related Arthritis: Who, What, Why, and How?