Effectiveness of adalimumab and secukinumab with and without concomitant csDMARD in psoriatic arthritis patients: retrospective cohort study

Psoriatic arthritis is a chronic condition where the body's immune system mistakenly attacks the joints, often in people who also have a skin condition called psoriasis. This attack causes pain, swelling, and stiffness, and if left unchecked, it can lead to permanent damage in the joints. To stop this, doctors use medicines that calm down the immune system. For a long time, the standard approach involved using older, well-known medicines first. If those did not work well enough, doctors would switch to newer, more powerful drugs called biologics. These newer drugs are highly effective, but they are also expensive and require careful monitoring. A lingering question in the medical community has been whether patients should stop the older medicines when they start the new ones, or if they should keep taking both together. Keeping both might offer extra protection, but it also means more pills, more blood tests, and a higher risk of side effects. Finding the right balance is crucial for helping patients live comfortably without unnecessary burden.

Researchers at the Sint Maartenskliniek in the Netherlands set out to answer this question by looking at real-world data from hundreds of patients. They focused on two specific types of powerful new drugs: adalimumab, which works by blocking a protein called tumor necrosis factor, and secukinumab, which targets a different protein known as interleukin-17. The team wanted to see if patients who kept taking their older medicines alongside these new drugs stayed on treatment longer than those who stopped the older medicines. In the world of rheumatology, staying on a drug for a long time is a strong sign that it is working well and that the patient is tolerating it without major problems. The researchers examined records from over 600 patients who started these treatments between late 2019 and early 2025. They carefully grouped the patients based on whether they took the new drug alone or combined it with an older medicine, such as methotrexate or leflunomide.

The results revealed a clear difference between the two types of new drugs. For patients taking adalimumab, those who continued their older medicines alongside it stayed on the treatment significantly longer. On average, patients who combined the drugs remained on adalimumab for fifteen months before stopping, compared to just eleven months for those who took it alone. The data showed that the risk of stopping the treatment early was much lower for the combination group. This suggests that for this specific drug, the older medicines provide a helpful boost, perhaps by making the new drug work better or by preventing the body from rejecting it. The researchers found this pattern held true even after accounting for factors like the patient's age and sex.

However, the story was completely different for secukinumab. When patients took this drug, it made no difference whether they also took an older medicine or not. Patients on secukinumab alone stayed on treatment for about the same amount of time as those who combined it with older drugs. In fact, the data showed no benefit to adding the extra medicine for this specific drug. The researchers noted that secukinumab is known to be very stable in the body and rarely triggers the immune system to fight back against the drug itself, which might explain why it does not need the extra help from older medicines. This finding is important because it suggests that for patients starting secukinumab, doctors might safely stop the older medicines, sparing patients from extra pills and monitoring without losing any of the treatment's effectiveness.

The study did not find a single rule that applies to all powerful new drugs. Instead, it showed that the best strategy depends entirely on which drug is being used. For adalimumab, keeping the older medicine on board appears to be the smarter move, extending the time the treatment works. For secukinumab, the older medicine adds no value to how long the treatment lasts. The researchers emphasized that their findings are based on how long patients stayed on the drugs, not on how well the drugs reduced pain or swelling in every single case, though staying on a drug is usually a good sign of overall success. They also noted that their study was observational, meaning they watched what happened in regular clinics rather than forcing patients into specific groups, which reflects real-life practice but leaves room for other factors to influence the results. Despite this, the clear difference between the two drugs offers a practical guide for doctors and patients. It points toward a more personalized approach where the decision to combine medicines is tailored to the specific drug chosen, ensuring patients get the most benefit with the least amount of unnecessary treatment.