Background/Purpose: Gout and calcium pyrophosphate crystal deposition disease (CPPD) are frequent in hospital settings. In Spain, last available data (2005-2015) indicated that 0.48% of hospital discharges had a gout diagnosis, with rising prevalence and mortality (PMID 34168227). Conversely, no population-based studies exist for CPPD. We aimed to analyze prevalence, hospital stays, mortality, and costs of hospitalized patients with gout or CPPD between 2016 and 2022 in Spain.

Methods: We used the Minimum Basic Data Set (MBDS) from the National Health Service to study adult patients with any primary or secondary diagnosis of gout (ICD-10-ES codes M10.X or M1A.X) or CPPD (M11.X) admitted to public or private hospitals between 2016 and 2022. Prevalence with 95% confidence intervals (CIs) and temporal trends were calculated over annual hospitalization discharges. Differences in age, sex, mean hospital stay, mortality, and costs (measured based on All Patient Refined Diagnosis-Related Groups) were analyzed between patients with gout and CPPD, stratified by being primary or secondary diagnoses. Kruskal-Wallis and chi-square tests were used for comparisons.

Results: After excluding 13,987 for errors in coding, we studied 183,001 patients in the 2016–2022 period. The prevalence of gout was 0.58% (n=167,693/28,861,486; 95%CI 0.58-0.58%), coded as primary diagnosis in 5,314 (3.2%) and secondary in 162,379 (96.8%). Meanwhile, the prevalence of CPPD was 0.05% (n=14,473/28,861,486; 95%CI 0.05-0.05%), mostly as secondary diagnoses (95%, n=13,752). 835 patients had both crystal diagnoses. Compared to gout, patients with primary or secondary CPPD were older (74.4±14.2 vs 70.8±14.3 years, p< 0.001; 79.7±10.9 vs 74.8±12.1 years, p< 0.001) with a female predominance (52.6% vs 15.8%, p< 0.001; 61.4% vs 16.5%, p< 0.001). The average age steadily increased up to +2.4 years in gout and +4.8 in CPPD in the study period. Mean hospital stay was significantly longer in gout than in CPPD (6.5±7 vs 5.6±5.3 days, p< 0.001). It decreased only for patients with secondary diagnoses of gout or CPPD (Gout: -0.7 days, p< 0.001; CPPD: -0.1 days, p=0.047). Mortality of inpatients with primary diagnosis was 0.7% in gout and 0.1% in CPPD (p< 0.001). In secondary diagnoses, respective mortalities were 6.1% and 4.7% (p< 0.001). Mortality showed a significant increase in gout (Primary Gout: +0.5%, p=0.02; Secondary Gout: +1%, p< 0.001), while only in secondary diagnoses of CPPD (+1.1%, p< 0.001). Costs were similar in gout and CPPD-related hospitalizations (3624.6±1794.66 € and 3645.40±1644.52 €), but higher for gout in secondary diagnoses (5318.5±5257.6 € vs 4933.9±4316.3 €, p< 0.001). In all cases, mean costs increase progressively.

Conclusion: The updated prevalence of gout in hospitalizations surpasses previous reports. Novel national CPPD data shows it occurs more frequently in older patients and women. Gout results in longer hospital stays and higher mortality. Hospitalizations, age, costs, and mortality rates rose during the study period, indicating a significant burden of crystal-related arthritis in hospitals.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/hospital-burden-of-crystal-related-arthritis-in-spain-a-nationwide-dataset-of-183001-inpatients/