Epidemiological trends of HIV infection in Spain

This cohort study (VAHC cohort) was conducted to evaluate temporal changes of HIV infection in Spain. The study enrolled 4335 HIV-positive patients. Results showed that the percentage of women with new diagnoses of HIV infection had increased in the past 3 years, that sexual transmission has overtaken the injection drug use mode of transmission in Spain since 1998, and that the percentage of new HIV diagnoses is increasing in older people (> 39 years old). The AIDS surveillance programme has been the system by which to monitor the HIV epidemic. In past years, as a consequence of the efficacy of highly active antiretroviral therapy, the natural history of the disease has been modified [1–3], and surveillance on AIDS cases has become an insufficient method to monitor the HIV epidemic. Cohort studies will allow the identification of new risk populations in order to implement preventative strategies and resource allocation for new prevention plans. This cohort study was conducted to evaluate the temporal epidemiological changes of HIV infection in Spain. The participant sites are 14 hospitals located in different geographical areas (VACH Group). The recruiter centres belong to the National Public Health System, of which seven are teaching hospitals. The study enrolled 4335 HIV-positive patients. All HIV-positive patients who came to our sites for their first outpatient visit from January 1997 to 31 December 2000 are included in the study, some of these patients were newly diagnosed at the time of the visit but others had been diagnosed with HIV in other hospitals before they came to our sites. The distribution of HIV-infected patients enrolled by regions was 33% from the south (Andalusia), 17% from the centre (including Madrid), 18% from the north (including Pais Vasco), and 33% from the east (Catalonia and Levante). The VACH sites cover approximately 14% of the total Spanish population. Each hospital uses common software (ACH) to enter the clinical and laboratory data of HIV-infected patients during each outpatient visit. The investigator from each site adhered to the study protocol, adopting the software as the unique procedure for recording data for their patients. The VACH Group developed standard operation procedures describing the processes to control the quality of the data. Data confidentiality is guaranteed by assigning a unique identifier code to each recruited patient, at the same time avoiding any duplication. Data are sent in an electronic CRF format, every 4 months, via e-mail, and are captured by the VACH Central Data Base. The Central Data Base was set up to detect any duplicates, mistakes and missing data by internal quality controls. A descriptive distribution of the main variables was calculated. For continuous variables, the medians were estimated. Calculations were based on the full group, except when cross-tabulating variables with missing data. Differences between age groups, sex and risk behaviour in each time of infection period were tested using the chi-square test. The percentage of HIV-infected women in the cohort is 21.7%. In the past 3 years the percentage of women with new diagnoses of HIV infection was 25.7 versus 14.8% (P < 0.0001) in the first decade of the infection (Table 1). New HIV-infected men, excluding men who have sex with men (MSM), have decreased from 85.2 to 73.3%, although the percentage of new diagnoses in MSM has increased twofold (P < 0.0001) from 1994.Table 1: Distribution of behavioural risk categories.The distribution of behavioural risk categories has changed with time (Table 1). The percentage of individuals who acquired HIV infection by intravenous drugs was 91.5% at the beginning of the epidemic (first decade); since then the percentage has decreased to 36.2%. In contrast, sexual transmission increased in both MSM (ninefold) and heterosexual individuals (10-fold) in the past decade. These data show that sexual transmission has overtaken the injection drug use mode of transmission in Spain since 1998. The majority of individuals affected by HIV still belong to a low economic class (52.6%) and have a low educational level (60.7%; no studies, 10.1%). The data on occupation show that 27.4% of HIV-infected patients have a job, whereas 32% are unemployed, but the proportion of newly diagnosed HIV working patients increased to 50.2% in the past 3 years. Around 1990, 71.8% of HIV-infected patients were 20–29 years old at the time of diagnosis, 13.7% were under 20 years of age, and 14.2% were 30–39 years old. Patients over 39 years old represented less than 1% of the total. In the second decade, the percentage of new HIV diagnoses increased to 40% in the 30–39 year age group (P < 0.0001), and the percentage of patients over 39 years of age had increased more than 30-fold (Table 2).Table 2: Frequencies of patients by age at HIV diagnosis and by date of HIV diagnosis.Our results reveal that very important epidemiological characteristics of HIV-infected patients in Spain have shifted significantly since the beginning of the epidemic. The increasing proportion of infected women is a finding consistent with similar studies [4]. The percentage of HIV patients infected by sexual transmission was 58.6%. This percentage overtakes transmission by intravenous drug use that was for a long time the most common mode of transmission in Spain. The tendency towards heterosexual transmission has been described before [5,6]. The increase in MSM also detected in some countries correlates with the increase in the incidence of rectal gonococcus along with the increase in high-risk sexual practices [7,8]. The temporal trends of new HIV cases by age group (age at diagnosis) show a relevant finding in the displacement of the age of diagnosis towards older age groups, 30–39 years and 40 years or older. This finding correlates with the data published on HIV surveillance in the United States [9]. Overall, this study represents the epidemiological trends of HIV infection in Spain, as the VACH cohort is the only Spanish cohort that included a large number of HIV-infected patients from 14 hospitals located in different geographical regions of the country. Several drawbacks in this study should be considered in order to interpret our results, because this work has the limitations described in any retrospective cohort study [10,11]. Although population studies are the gold standard to follow the epidemiology of HIV, this cohort study provides some clues to a better understanding of where the trends of the epidemic are going. These clues can help to re-direct preventative and educational campaigns to adult populations at risk. We conclude that HIV diagnoses in Spain are increasing in women and MSM. The heterosexual mode of transmission is increasing over injection drug use and MSM, and HIV infection is moving towards older population groups (30–39 and > 39 years old).