Age>18 years, without communication problems and who agreed to participate in the study by signing a written informed consent. The patients were included consecutively.

The case report form (CRF) included sociodemographic variables (civil status, cohabitation, educational level, employment situation, identification of the person who contributed the most income to the household, social class, self-perceived health status, comorbidities, body mass index (BMI), smoking habit, and physical activity) used by the Ministry of Health and the National Statistics Institute (NSI)16,17 in their population health surveys. Likewise, the CRF asked the patients if they had had any other diseases diagnosed by a doctor in the last 12 months, from a list of 32 diseases. To explore alcohol consumption, the AUDIT-C questionnaire18,19 was used. To measure the degree of health literacy, the 16-item European Health Literacy Survey Questionnaire (HLS-EU-Q16) validated in Spain20 was used. The instrument for measuring HRQoL was the EQ-5D-5L, used in the Spanish National Health Survey (ENSE) 2011–2012,16,17,21 which was the last ENSE that measured HRQoL in adults.

Based on the ICD-10 classification of “diseases of the musculoskeletal system and connective tissue”, seven diagnostic categories were established: peripheral and axial mechanical pathology; soft tissue pathology; neuropathies; metabolic pathology; infectious pathology; inflammatory and microcrystalline arthropathies; and vasculitis-connective tissue diseases. Each of these categories was subdivided into their corresponding diagnostic subcategories.22 As some patients could have more than one rheumatic disease, the variables “main diagnosis” and “secondary diagnosis” were created with the same category structure. The diagnosis, in turn, was classified as confirmed or suspected. The doctor filled out a database (DB) with information from the MR.

To obtain a precision of 3% in the categorical variables, with the assumption of maximum indeterminacy (p=q=0.5), 1056 patients would have been necessary (α=0.05; β=0.8). The mean VAS of the EQ-5D-5L in the ENSE was 77.9 (standard deviation (SD)=18.6).21 If in the RS-RyCUH, the VAS obtained had a variance similar to that obtained in a study carried out in Portugal (mean: 60.7; SD=19.3),23 904 patients would be necessary to find a difference of 2.5 points between the hospital sample and the general population. For these reasons, a sample size with sufficient power and statistical precision of around 1000 patients was considered.

The CRF draft version was tested in a pilot study with 5 patients, after which the final CRF version was prepared in paper format. Trained personnel (auxillary nurses) assisted patients with the CRF when required. The information collected through the CRF and the MR was entered in the DB.

For the descriptive analysis, categorical variables were described as proportions (%). To describe the continuous variables, the normality of their distribution was first verified using the Kolmogorov–Smirnov test. For continuous variables with a normal distribution, the mean and SD were used. For continuous variables without a normal distribution, the median and interquartile range (IQR) were used. To fully illustrate the distribution of non-normally distributed continuous variables, the mean and SD were also shown.

HRQoL was described using the categorical and continuous EQ-5D-5L variables. The five categorical variables included the proportion of patients who reported a problem in each of the 5-dimensions of the EQ-5D-5, and the continuous variables were the VAS and the EQ-Index.24

As the VAS and EQ-Index did not have a normal distribution, the study of univariate associations of the VAS and EQ-Index with gender and age groups was performed using the Mann–Whitney U test (two samples), or the Kruskal–Wallis test (more than two samples). Finally, the patients’ HRQoL was compared with the HRQoL of the Spanish adult population according to the ENSE,21 and between the subgroups for which information was available. In this comparison, the t-test was used for two independent samples, since the ENSE data only included the number, mean, and SD.

The contrasts were made with two tails and a p<0.05 was considered a statistically significant association. Data analysis was performed using the SPSS statistical package (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.).

The patient was informed that their responses would be anonymized. The patients who agreed to participate signed the written informed consent and completed the CRF. The anonymized data were included in the DB and were processed with the security measures established in the Data Protection Law.25 The researchers preserved the confidentiality of the data as determined by the Law on Patient Autonomy, Clinical Information and Documentation.26 The research protocol was approved by the Ramón y Cajal University Hospital ethics and clinical research committee (Code 072-20).

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

From January 2020 to December 2021, 1144 patients were included in the study, with a mean age of 56.10 years, of whom 820 (71.68%) were women. The most frequent civil status was married (51.71%) with a predominance of patients with university or equivalent studies (36.00%). The health literacy questionnaire was completed by 931 patients, of which 34.8% had a problematic or inadequate health literacy level. Regarding employment situation, the group that works for their own account or for others (45.77%) predominated, and in 51.75% of households, the person who contributed the highest income was the patient. The questionnaire on social class (defined according to the professional group to which the person who contributes the most income to the household belongs) was answered by 974 patients, and the majority (24.02%) belonged to class V (qualified worker) (Table 1).

Regarding lifestyle habits, 14.19% of the patients were smokers and no patients had risky consumption of alcohol. The predominant degree of physical activity was “occasional physical or sports activity” (52.87%), followed by “sedentary activity” (24.07%). The BMI could be calculated in 1019 patients, of whom 36.80% were overweight and 18.45% were obese (Table 1).

A quarter of the patients attended the consultation for the first time, and the rest went for a follow-up visit. All patients had a primary diagnosis and 507 (44.32%) patients had a secondary diagnosis.

The most frequent main diagnosis was inflammatory and microcrystalline arthropathies (37.33%), followed by peripheral and axial mechanical pathology (23.16%) and connective tissue diseases and vasculitis (20.02%). In 95.1% of the patients, the main diagnosis was confirmed. The most frequent secondary diagnosis was diseases in the peripheral and axial mechanical pathology group (50.1%), followed by the soft tissue pathology group (24.46%); 96.41% of the secondary diagnoses were confirmed (Table 2).

With respect to perceived state of health in the last 12 months, 37.39% of patients reported it was good or very good, 42.06% fair, and 20.55% bad or very bad (Table 2).

The three most frequent diseases were rheumatological: chronic back pain (lumbar) (45.80%); osteoarthritis (excluding arthritis) (38.46%); and chronic back pain (cervical) (35.84%). After these, the most frequent were high cholesterol (27.27%) and high blood pressure (26.66%) (Supplementary Table 1). A minority of patients, 6.52%, stated they did not suffer from any of the 32 diseases included in the questionnaire (assuming those who answered no or did not respond did not suffer from the disease), 10.10% declared they had one, 13.76%, two, 69.62%, three or more, and 44.06% declared having five or more diseases. The median number of diseases diagnosed by a doctor per patient in the previous year was 4 (IQR: 2–6) (Supplementary Table 2). The number of illnesses per patient was significantly higher in RS-RyCUH patients than in the general population (Table 3).

Over half of the patients, 52.50%, declared having a problem in the “mobility” dimension of the EQ-5D-5L, 25.16% in “self-care”, 51.38% in “daily activities”, 84.08% in “pain/discomfort” and 52.75% in “anxiety/depression” (Supplementary Table 3). The proportion of patients with problems in each of the dimensions was higher than in the general Spanish population (Table 4).

The VAS had a mean of 65.26 (SD: 21.54), and a median of 70 (IQR: 50–80). The VAS was higher in men (mean 69.31) than in women (mean 63.60) (p=0.000; Mann–Whitney U test), and lower with increasing age. For example, in patients aged 18–24 years old it was 78.31, and in subjects over 85 years old it was 48.55 (p=0.000; Kruskal–Wallis test). The mean VAS of the patients (65.26) was lower than that of the general population (77.53) (p=0.000), and also when compared by gender and age, except in those>85 years of age, in which the 6-point difference did not reach statistical significance (p=0.162) probably due to the small number of patients of this age (Table 5).

The EQ-Index was calculated for 1059 patients (mean 0.728; SD: 0.226; median 0.776; IQR: 0.625–0.899). The EQ-Index was higher in men (mean 0.788) than in women (mean 0.703) (p=0.000; Mann–Whitney U test), and tended to be lower with advancing age. For example, in patients between 18 and 24 years old it was 0.858, while in subjects over 85 years old it was 0.473 (p=0.000; Kruskal–Wallis test). The mean EQ-Index in the patients (0.728) was lower than that of the general Spanish population (0.914) (p=0.000), and also when compared by gender and age (Table 5).