The relationship between dietary inflammatory index and disease activity and biochemical parameters in individuals with psoriatic arthritis

This study was conducted to investigate the relationship between the Dietary Inflammatory Index (DII), disease activity, and certain biochemical parameters in individuals diagnosed with psoriatic arthritis (PsA), based on the CASPAR (Classification Criteria for Psoriatic Arthritis) criteria. The research was carried out between November and December 2024 with 100 volunteers aged 18–75 who had previously been diagnosed with PsA and visited the Rheumatology Outpatient Clinic of Başkent University Ankara Hospital for follow-up. Sociodemographic characteristics and general disease-related information were assessed using a questionnaire. Anthropometric measurements and three-day dietary intake records were obtained from the participants. Disease activity was evaluated using the Visual Analog Scale (VAS), Health Assessment Questionnaire (HAQ), and Disease Activity in Psoriatic Arthritis (DAPSA) score, along with biochemical parameters. Participants were categorized into two groups based on their DAPSA scores: those with DAPSA < 15 were classified as the active disease group, and those with DAPSA ≥ 15 as the inactive disease group. Average daily nutrient intake from the dietary records was used to calculate the DII. Participants' DII scores were divided into tertiles. As the tertile number increased, the inflammatory potential of the diet increased; the first tertile represented an anti-inflammatory diet, whereas the third tertile indicated a pro-inflammatory diet. In the active group, the median DII score in the first tertile was -10.0 [IQR: 2.0], ranging from -11.0 to -9.0. In the second tertile, the median was -6.6 [1.3], with a range of -7.1 to -5.8. In the third tertile, the median was -2.3 [2.6], with values ranging from -3.7 to 1.0. Among inactive individuals, the median DII score in the first tertile was -10.8 [2.7], ranging from -12.2 to -9.5; in the second tertile, the median was -6.4 [2.6], ranging from -7.7 to -5.1; and in the third tertile, the median was -3.4 [2.3], with minimum and maximum values of -4.8 and -1.5, respectively. Again, as tertile rank increased, the inflammatory burden of the diet increased. There were no statistically significant differences between DII tertiles and participants' age, body mass index (BMI), waist circumference, waist-to-hip ratio, waist-to-height ratio, triceps skinfold thickness, mid-upper arm circumference, or smoking status (p > 0.05). In the active patient group (n = 52), no statistically significant correlation was found between DII and any biochemical parameter (p > 0.05). However, in the inactive group, significant positive correlations were observed between DII and both blood urea nitrogen (BUN) (r = 0.349, p = 0.019) and creatinine (r = 0.383, p = 0.009). No significant relationship was found between serum C-reactive protein (CRP) levels and total DII scores in either group (p > 0.05). Significant associations were observed between anthropometric measurements and disease activity (DAPSA score) in both active and inactive groups (p < 0.05). Additionally, a statistically significant correlation was found between DAPSA and HAQ scores in both groups (p < 0.05). In conclusion, the management of factors affecting both disease severity and quality of life in individuals with psoriatic arthritis necessitates a holistic approach. In addition to pharmacological treatment, the promotion of anti-inflammatory dietary patterns, the development of strategies to combat obesity and comorbidities, and the enhancement of patients' lifestyle awareness are among the key elements that may contribute to improved clinical outcomes.