In this population-based study, we examined the the temporal trends in the prevalence and incidence of PsA in a large datsbase in Israel from 2016 to 2022. The age and sex standardized prevalence and incidence rates were calculated using the 2006 Israeli population to allow a direct comparison to the rates provided in the previous study. We observed that in 2022, the prevalence of PsA in the adult population in Israel was 0.221% with an incidence rate of 13.54 per 100,000 population. The reported prevalence of PsA in Israel has tripled since 2006, rising from 0.067% in 2006 to 0.221% in 2022. The global incidence rate has also relatively increased from 10.4 (95% CI 9.5–11.4) in 2006 to 15.5 (95%CI 14-16.8) in 2021 and 13.5 (95%CI 12.2–14.8) in 2022 and that PsA was more commonly found in individuals from specific groups, including females, Jewish ethnicity, higher SES, higher BMI and among smokers.

Most population-based epidemiological studies on PsA have focused on European populations, leaving a significant gap in our understanding the disease prevalence in other ethnic groups and geographic regions, particularly in Middle Eastern populations.

To the best our knowledge, this study stands as the largest-scale population-based research providing insights into PsA prevalence in a Middle Eastern population, encompassing two diverse subpopulations.

Our estimated PsA prevalence in Israel (0.221%) falls above the prevalence range reported in a systematic review and meta-analysis (0.13%) the general population [4], but aligns more closely with estimates in the United States (0.25%)[14], Ontario[15] and Northern European countries such as Sweden (0.25%)[16], Norway (0.19–0.67%)[17, 18], the United Kingdom (0.19%)[5].

Discrepancies in prevalence estimates between studies are attributed to factors like differences in study design, case definitions (self-reported or database-derived), genetic backgrounds, environmental factors (including climate and infections), lifestyle (smoking, alcohol consumption, and obesity), and dietary habits (such as adherence to the Mediterranean diet and fish oil consumption).

Notably, the prevalence of PsA varies in other Mediterranean countries, ranging from 0.05% in Turkey[19], to 0.06–0.17% in Greece[20, 21].

Fewer studies have explored the incidence of PsA. Our estimated incidence rate of cases per 100,000 population falls within the range of previous estimates in most European and US populations, which typically range from 6 to 35.9 per 100,000 [4].

Traditionally, the proportion of male and female PsA patients has been considered roughly equal. However, slight variations in sex proportions have been reported in different studies. [4] In our study we observed a slight female predominance (0.233% vs. 0.209%) and both sexes exhibited an increasing incidence over time.

The prevalence of PsA among patients with psoriasis in our study was 16.48%, compared to a pooled PsA prevalence of 19.7% (95% CI 18.5–20.9%) in patients with psoriasis in a 2019 systematic review and meta-analysis.[22].

Our study demonstrates an increasing trend in the crude and age-adjusted prevalence and incidence of PsA over the study period. These findings align with recent research from Europe and Asia that has reported a rise in the prevalence and incidence of psoriasis and PsA over time[23,24,25]. Possible factors contributing to this trend include increased disease awareness among physicians, possibly driven by the 2006 Classification Criteria for Psoriatic Arthritis (CASPAR) criteria, which heighlighted awarness and recognition of PsA and might have lead more rheumatologists to classify a disease as “PsA” rather than “spondyloarthritis”. Morever, the enhanced and increased utilization of use of an advaced and sensitive diagnostic modalities (e.g., ultrasound and magnetic resonance imaging- MRI) could have impacted PsA diagnosis. Additionally, both international and local educational initiatives among rheumatologist and primary care physicians as well as rheumatologist and dermatology specialists (Group for Research and Assessment of Psoriasis and psoriatic arthritis -GRAPPA) has led to an increase in disease awareness and more referral to a rheumatologist.

Other potential drivers for the rise in PsA prevalence could be the decrease in disease mortality over the past decades, that could be the as a result of improvement in disease management and treatments over the years. Additionally, the increased presence of known risk factors like obesity in Israel [26, 27] and shifts in population demographics such as immigration of high-risk groups could have also impacted these trends.

Moreover, greater availability of effective medications can also lead to more individuals seeking medical advice and consequently being diagnosed with the disease.

Various demographic factors were found to be correlated with the occurrence of PsA including sex, ethnicity, SES, BMI and smoking status. The prevalence of PsA was higher in females, consistent with studies that showed higher incidence of PsA in females[22, 28]. Nevertheless, the data on sex ratio also appears disparate. PsA was also nearly 1.6 times more prevalent in the Jewish population compared to Arabs, as well as among individual with higher SES. These disparities may be attributed to differences in genetics, environmental exposures, or healthcare utilization.

Furthermore, our findings confirm the association of obesity with a nearly twofold increase in PsA prevalence, aligning with the existing literature. [29, 30]

Additionally, our study suggests an association of smoking with PsA (adjusted OR of 1.42; 95% CI 1.35–1.49). However, these results should be interpreted with cation as we didn’t account for psoriasis as a causal intermediate variable. Thus, smoking might indirectly elevate the risk of PsA by increasing the risk of psoriasis, potentially leading to spurious findings. Smoking is well-known risk factor for psoriasis; yet its link to the development of PsA has produced varying results in prior research [31, 32].

Our study carries several limitations. We could not capture patients with PsA or psoriasis who did not seek medical attention or those who remained undiagnosed. Additionally, our case definition relies on diagnostic coding from electronic medical records based on physician diagnoses, which carries the risk of misclassification. Nonetheless, we minimized this risk by employing an algorithm with high accuracy that largely relied on specialist diagnoses.

A significant strength of our study is the use of a large, representative sample covering over half the Israeli population, allowing for broad generalization of our findings.