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S Pérez-Hoyos

Publications and source records attributed to S Pérez-Hoyos.

At least 19 recordsLinked to original sources
PubMed2006

Effect of education on overall and cause-specific mortality in injecting drug users, according to HIV and introduction of HAART.

BACKGROUND: We assessed the impact of education on long-term overall and cause-specific mortality among 6575 injecting drug users (IDUs) according to HIV status and introduction of highly active antiretroviral therapy (HAART). METHODS: Community-based cohort study of IDUs recruited in three AIDS prevention centres (1987-1996). Causes of death were ascertained in clinical centres and Mortality Registry and classified as AIDS, drug use related, injuries, or liver diseases. Poisson regression models including education and calendar period interaction and adjusted by sex, age, and HIV were used. RESULTS: In 73 901 person-years of follow-up, there were 1493 deaths (20.2/1000 person-years): 761 related to AIDS, 234 to drug use, 179 to injuries, and 93 to liver diseases. IDUs with university studies had a lower risk of death (RR 0.52; 95% CI 0.36-0.77) than those without studies: this difference was higher after (RR 0.45; 95% CI 0.25-0.80) than before 1997 (RR 0.68; 95% CI 0.41-1.13). Compared to before 1997, while decreases in the risk of AIDS mortality were seen during 1997-2004 for both lower (RR 0.49; 95% CI 0.41-0.58) and higher (RR 0.33; 95% CI 0.23-0.48) educated, only those higher educated experienced a reduction in drug-use mortality (RR 0.54; 95% CI 0.28-1.05) and death from injuries (RR 0.52; 95% CI 0.23-1.21). CONCLUSIONS: Independently of HIV status, lower education predicts a higher risk of death in IDUs and its impact is stronger after 1997. Education has a protective effect on most causes of death and it cannot be entirely attributable to the access or use of HAART.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Trends in HIV testing, serial HIV prevalence and HIV incidence among people attending a Center for AIDS Prevention from 1988 to 2003.

AIM: To analyse trends in HIV testing, serial HIV prevalence and HIV incidence among people who underwent voluntary testing in a Center for AIDS Prevention in Valencia, Spain. METHODS: Open cohort study including all subjects who went to the Center for AIDS Prevention from 1988 to 2003. Information on sociodemographic variables and HIV test results was collected. Serial prevalence and incidence rates were calculated, and joinpoint regression was used to identify changes in trends over time. RESULTS: 21,241 subjects were analysed; 67% men, 27% injecting drug users (IDUs), 43% heterosexuals and 13% men who have sex with men (MSM). From 1988 to 1990, IDUs accounted for 57% of clinic attenders, decreasing to 14% by 1997-2003, accompanied by an increase in heterosexuals. Overall, HIV prevalence for the whole period was 15%, dropping from 35% to <10% after 1999 and to 3% by 2003, when HIV prevalence was 26% in IDUs, 6% in MSM and 2% in heterosexuals. Total HIV incidence was 2.5%. From 1988 to 1990, HIV incidence ranged from 6% to 8%, and a gradual and progressive decline observed from 1990 onwards. From 1995 onwards, HIV incidence was <2%. The highest incidence rate is seen in IDUs, 7-12% in the first period and 4-5% at the end. Among MSM, a change in the decreasing trend is seen by 1998, and increases in incidence are detected by 2002-3. CONCLUSIONS: Serial HIV prevalence has markedly decreased from 1988 in all transmission categories, although it is still high. With regard to HIV incidence, the drop has been marked too, although a worrying increase, that requires further follow-up, has been detected in MSM in the past 2 years.

Adolescent↗
PubMed2006

Psychosocial work environment and burnout among emergency medical and nursing staff.

OBJECTIVES: The prevalence of burnout syndrome is increasing among doctors and nurses. The aim of this study was to analyse the relationship between the psychosocial work environment and burnout syndrome among emergency medical and nursing staff in Spain. A secondary aim was to determine if the effect of this psychosocial work environment on burnout was different for doctors and nurses. METHODS: A cross-sectional survey was carried out by means of a mail questionnaire among 945 emergency doctors and nursing staff of Spain. The outcome variable was three dimensions of burnout syndrome [emotional exhaustion (EE), personal accomplishment (PA), depersonalisation (DP)]. The explanatory variable was that psychosocial work environment evaluated according to Karasek and Johnson's demand-control model. The adjusted odds ratios (OR) and their 95% confidence intervals were calculated by logistical regression. RESULTS: The probability of high EE was greater among those exposed to high psychological demands, OR 4.66 (2.75-7.90), low job control, OR 1.65 (1.04-2.63), and low supervisors' social support, OR 1.64 (1.01-2.59). Emotional exhaustion dimension was negatively influenced by low control only among doctors. Those exposed to low job control had a higher risk of low PA, OR 2.55 (1.66-3.94). There was no evidence of negative effect of psychosocial risk factors on the DP. Prevalence of EE and PA was higher among doctors and nurses. CONCLUSIONS: The presence of risk factors derived from work organisation within the work place (psychosocial risk factors) increases the probability of presenting burnout syndrome and, above all, EE.

Adult↗
PubMed2006

Air pollution and cardiovascular admissions association in Spain: results within the EMECAS project.

OBJECTIVE: To evaluate the short term effect of air pollution on cardiovascular admissions in 14 Spanish cities METHODS: The period under study was from 1995 to 1999. Daily emergency admissions for all cardiovascular diseases (CVD) and heart diseases (HD) were obtained from hospital records, and the corresponding daily levels of particulates, SO2, NO2, CO, and ozone were recorded. The magnitude of association was estimated using Poisson generalised additive models controlling for confounding and overdispersion. For each cause, lagged effects, up to three days, of each pollutant were examined and combined estimates were obtained. For ozone the analyses were restricted to the warm period. One and two pollutant models were performed. RESULTS: Associations were more consistent in lag 0 (concurrent day) and 1 (lag 0-1), except in the case of ozone where there was a more delayed relation (lag 2-3). For combined estimates an increase of 10 microg/m3 in the PM10 levels in lag 0-1 was associated with an increase of 0.9% (95% CI: 0.4 to 1.5%) in the number of hospital admissions for CVD, and 1.6% (0.8 to 2.3%) for HD. For ozone the corresponding estimates for lag 2-3 were 0.7% (0.3 to 1.0) for CVD, and 0.7% (0.1 to 1.2) for HD. An increase of 1 mg/m3 in CO levels was associated with an increase of 2.1% (0.7 to 3.5%) in CVD admissions, and 4.2% (1.3 to 7.1%) in HD admissions. SO2 and NO2 estimates were more sensitive in two pollutant models CONCLUSIONS: A short term association between increases in daily levels of air pollutants and the number of daily admissions for cardiovascular diseases, with specificity for heart diseases, has been described in Spanish cities.

Aged↗
PubMed2003

A strong decrease in Saturn's equatorial jet at cloud level.

The atmospheres of the giant planets Jupiter and Saturn have a puzzling system of zonal (east-west) winds alternating in latitude, with the broad and intense equatorial jets on Saturn having been observed previously to reach a velocity of about 470 m x s(-1) at cloud level. Globally, the location and intensity of Jupiter's jets are stable in time to within about ten per cent, but little is known about the stability of Saturn's jet system. The long-term behaviour of these winds is an important discriminator between models for giant-planet circulations. Here we report that Saturn's winds show a large drop in the velocity of the equatorial jet of about 200 m x s(-1) from 1996 to 2002. By contrast, the other measured jets (primarily in the southern hemisphere) appear stable when compared to the Voyager wind profile of 1980-81.

Journal Article↗
PubMed2003

Progression of HIV infection and mortality by hepatitis C infection in patients with haemophilia over 20 years.

Hepatitis C virus (HCV) infection is an important cause of mortality in human immune deficiency virus (HIV)-positive haemophiliacs. This study describes progression to AIDS, death from HCV end-stage liver disease (ESLD) and all-cause mortality over 20 years. All HIV-positive haemophiliacs in La Paz University Hospital were included in this cohort. HIV seroconversion was estimated using mathematical techniques for interval-censored data from 1979 to 1985. Poisson regression was used to estimate rates of AIDS, death from ESLD and all causes in different periods: before 1988, 1988-89, 1990-91, 1992-93, 1994-95, 1996-97 and 1998-2001 using competing risk models. Among 383 cohort members, global AIDS incidence was 9.7 per 100 person-years, peaking in 1992-93 and dropping by 87% in 1998-2001 compared with before 1988 [incidence rate ratio (IRR) 0.13; 95% CI: 0.03-0.53]. Overall mortality was 7.5 per 100 person-years, was highest from 1992 to 1997, and fell by 66% in 1998-2001 compared with before 1988 (IRR 0.34; 95% CI: 0.14-0.81). Eighteen (5%) persons died of ESLD which represented 19% of deaths before 1988, 4% during 1988-89, 1990-91 and 1992-93, 2% in 1994-95, 10% in 1996-97 and 33% in 1998-2001. Overall death rate from ESLD was 0.5 cases per 100 person-years with no statistically significant trend observed over time. Important reductions in HIV disease progression to AIDS and death have been observed from 1998 to 2001, and can be attributed to highly active antiretroviral therapy. Although no increase in the rate of HCV-related deaths can be demonstrated, HCV accounts for an increasing proportion of deaths in the recent years.

Acquired Immunodeficiency Syndrome↗
PubMed2002

The EMECAM project: a multicentre study on air pollution and mortality in Spain: combined results for particulates and for sulfur dioxide.

OBJECTIVE: The EMECAM study is a collaborative effort to evaluate the impact of air pollution on mortality in Spain. In this paper the combined results are presented for the short term effects of particulates and sulfur dioxide on both daily mortality for all and for specific causes. METHODS: The relation between daily mortality for all causes, cardiovascular diseases, and respiratory diseases, and air pollution for particulates (daily concentrations) and SO(2) (24 and 1 hour concentrations) was assessed in 13 Spanish cities for the period 1990-6. With a standardised method, magnitude of association in each city was estimated by Poisson regression in a generalised additive model. Local estimates were obtained from both single and two pollutant analyses. Lastly, combined estimates for each cause and pollutant were obtained. RESULTS: For combined results, in single pollutant models a 10 microg/m(3) increase in the concentration of the mean of the concurrent and one day lag for black smoke was associated with a 0.8% (95% confidence interval (95% CI) 0.4 to 1.1%) increase in total mortality. The estimates for total suspended particles (TSPs) and particulate matter of aerodynamic diameter <10 microm (PM(10)) and total mortality were slightly lower. The same increase in concentrations of SO(2) was associated with a 0.5% increase in daily deaths. For groups of specific causes, higher estimations were found, specially for respiratory conditions. Peak concentrations of SO(2) showed significant associations with the three groups of mortality. When two pollutant analyses were performed, estimates for particulates, specially for black smoke, did not substantially change. The estimates for daily concentrations of SO(2) were greatly reduced, but, on the contrary, the association with peak concentrations of SO(2) did not show any change. CONCLUSIONS: There is an association between mortality and pollution through particulates among city populations in Spain. Peak rather than daily concentrations of SO(2) were related to mortality. Results suggest that populations in Spanish cities are exposed to health risks derived from air pollution.

Air Pollutants↗
PubMed2002

Factors influencing HIV progression in a seroconverter cohort in Madrid from 1985 to 1999.

OBJECTIVE: To study HIV progression from seroconversion over a 15 year period and measure the population effectiveness of highly active antiretroviral therapy (HAART). METHODS: A cohort study of people with well documented dates of seroconversion. Cumulative risk of AIDS and death were calculated by extended Kaplan-Meier allowing for late entry. Cox proportional hazards models were used to study variables associated with HIV progression. To assess the impact of HAART, calendar time was divided in three periods; before 1992, 1992-6, and 1997-9. RESULTS: From January 1985 to May 2000, 226 seroconverters were identified. The median seroconversion interval was 11 months, median seroconversion date was March 1993. 202 (89%) were men, 76% of whom were homo/bisexual. A 66% reduction in progression to AIDS was observed in 1997-9 compared to 1992-96 (HR 0.34 95% CI: 0.16 to 0.70). People with primary education appeared to have faster progression to AIDS compared to those with university studies (HR 2.69 95%CI: 1.17 to 6.16). An 82% reduction in mortality from HIV seroconversion was observed in 1997-9 (HR 0.18 95% CI: 0.05 to 0.68) compared to 1992-6. Progression to death for people with primary education was twice as fast as for those with university education (p 0.0007). People without confirmation of an HIV negative test had faster progression (HR 4.47 95% CI: 1.18 to 16.92). CONCLUSIONS: The reduction in progression to AIDS and death from seroconversion from 1992-6 to 1997-9 in Madrid is likely to be attributable to HAART. HIV progression was faster in subjects with primary education; better educational level may be associated with better adherence to medication.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Delayed motherhood increases the probability of sons to be infertile.

PURPOSE: To ascertain whether advanced maternal age at birth is associated with offspring infertility. METHODS: A written questionnaire was completed by infertile couples attending our clinic in the presence of a researcher. RESULTS: Maternal age at birth (odds ratio 1.236, 95% CI 1.100-1.388) and birth order of all respondents and their respective siblings (odds ratio 0.551, 95% CI 0.351-0.865) were significant predictors of male infertility. The probability of a man being infertile increased as mother's age at birth increased (regression coefficient +/- standard error 0.212 +/- 0.059; P < 0.001), but decreased as birth order increased (regression coefficient +/- standard error -0.596 +/- 0.230; P = 0.010). CONCLUSIONS: Delayed motherhood may enhance the probability of sons to be infertile. The probability of a man being infertile would be greater if he comes from a small family than if he comes from a large family.

Female↗
PubMed2001

Measures to reduce HIV infection have not been successful to reduce the prevalence of HCV in intravenous drug users.

The objective of the study was to determine whether measures taken to prevent human immunodeficiency virus (HIV) infection also lead to a reduction in the prevalence of hepatitis C virus (HCV) infection among intravenous drug users (IDU). Antibodies to HCV, HIV and hepatitis B virus (HBV) were determined in IDU who voluntarily attended AIDS prevention and information centres for the first time between 1990 and 1996. Of the 5473 IDU studied, determination of HCV was done in 3238 cases. The prevalence of antibodies to HCV was 85%. During the first period studied (1990-1992), the prevalence of antibodies to HCV was 84.5%, during the second (1993-1994) 84.1% and during the third (1995-1996) 87%; in the case of HBV the prevalence during the three periods was 74.5, 67.6 and 66.8% respectively, and for HIV it was 41.9, 38.8 and 36.6% respectively (RR: 0.72; 95% confidence interval (CI): 0.65-0.81). Among drug users addicted for less than 2 years, the trend of the prevalence of antibodies to HCV and HBV remained constant, while the prevalence of HIV infection decreased (RR: 0.61; 95% CI: 0.42-0.89). Measures to prevent transmission of HIV in drug users do not lead to a reduction in the prevalence of HCV infection. Further study is necessary to obtain a better understanding of how HCV is transmitted among drug users in order to apply measures which are effective in preventing HCV infection.

Adult↗
PubMed2001

Air pollution and emergency hospital admissions for cardiovascular diseases in Valencia, Spain.

STUDY OBJECTIVE: To estimate the short-term association between air pollution levels and emergency hospital admissions for cardiovascular diseases in Valencia, within 1994-1996 period. DESIGN: Daily levels of air pollution and emergency admissions for cardiovascular diseases were related to using an ecological time series design. The number of admissions was obtained from the hospital records database. Selected groups of causes were all cardiovascular diseases, heart admissions, and admissions for cerebrovascular diseases. The number of admissions for digestive diseases was used as control. Pollutants were black smoke, sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), carbon monoxide (CO) and ozone (O(3)). Magnitude of association was estimated by Poisson autoregressive regression. Estimations were calculated according the hottest (May to October) and the coldest (November to April) periods. SETTING: City of Valencia, Spain, about 750,000 inhabitants. PARTICIPANTS: People being admitted to the two major hospitals in the city, with a catchment area of nearly 400,000 inhabitants. MAIN RESULTS: For the whole period, a significant association for SO(2)-24 h was found so a rise in its levels of 10 microg/m(3) was associated with an increment of 3% (95%CI 0.4 to 5.7%) in the expected number of cardiovascular admissions. A significant association for black smoke, SO(2)-24 h, SO(2)-1 h, and CO-1 h was found in the hottest semester. All these associations were verified with a lag of two days. The estimates of the associations for particles, SO(2), and CO were affected by the inclusion of the other pollutants in their models. NO(2) was independently associated with cerebrovascular admissions. There were no significant associations between air pollution and admissions for digestive diseases. CONCLUSIONS: Current levels of air pollution and emergency cardiovascular admissions are significantly related in Valencia.

Air Pollutants↗
PubMed2001

Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities.

STUDY OBJECTIVE: The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches. DESIGN: The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992-1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models. MAIN RESULTS: The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 microg/m(3) and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10 microg/m(3) of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables. CONCLUSIONS: Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.

Air Pollutants↗
PubMed2001

The concentration-response relation between air pollution and daily deaths.

Studies on three continents have reported associations between various measures of airborne particles and daily deaths. Sulfur dioxide has also been associated with daily deaths, particularly in Europe. Questions remain about the shape of those associations, particularly whether there are thresholds at low levels. We examined the association of daily concentrations of black smoke and SO(2) with daily deaths in eight Spanish cities (Barcelona, Bilbao, Castellón, Gijón, Oviedo, Valencia, Vitoria, and Zaragoza) with different climates and different environmental and social characteristics. We used nonparametric smoothing to estimate the shape of the concentration-response curve in each city and combined those results using a metasmoothing technique developed by Schwartz and Zanobetti. We extended their method to incorporate random variance components. Black smoke had a nearly linear association with daily deaths, with no evidence of a threshold. A 10 microg/m(3) increase in black smoke was associated with a 0.88% increase in daily deaths (95% confidence interval, 0.56%-1.20%). SO(2) had a less plausible association: Daily deaths increased at very low concentrations, but leveled off and then decreased at higher concentrations. These findings held in both one- and two-pollutant models and held whether we optimized our weather and seasonal model in each city or used the same smoothing parameters in each city. We conclude that the association with particle levels is more convincing than for SO(2), and without a threshold. Linear models provide an adequate estimation of the effect of particulate air pollution on mortality at low to moderate concentrations.

Adolescent↗
PubMed2000

[Failure of an educational intervention to change anticholesteremic drug prescription in primary care].

OBJECTIVE: To evaluate the effectiveness of an intervention for decreasing hypocholesterolemic drugs prescription in patients with low cardiovascular risk profile. DESIGN: Quasi-randomized intervention study. SETTING: Public primary health care centres in the province of Valencia (Spain). PARTICIPANTS: 238 general/family practitioners from 23 primary health care centres. INTERVENTIONS: The centres were assigned to either an experimental group that received the educational intervention (individual scientific information by outreach detailing and invitation to a workshop about treatment of hypercholesterolemia in the primary care setting with the participation of an opinion leader) or a control group. MEASUREMENTS AND MAIN RESULTS: The effectiveness of the intervention was measured through the monthly mean daily defined doses (DDD) from the 4 months prior to the intervention until 5 months thereafter. Mean DDD increased along the study period in both groups, with no detectable differences between them. Similarly, there were no between-group differences after controlling the initial prescription levels using a mixed lineal model. CONCLUSIONS: The educational intervention as it was implemented was ineffective for changing overall hypocholesterolemic drug prescription in primary care. Consequently, this intervention is not justified for reducing pharmaceutical expenditure.

Anticholesteremic Agents↗
PubMed2000

Length of stay in a hospital emergency room due to asthma and chronic obstructive pulmonary disease: implications for air pollution studies.

The aim of this paper is to model the length of stay following hospital emergency due to asthma and chronic obstructive pulmonary disease (COPD) as well as those factors relating to its duration. Clinical records of all those hospital emergencies for asthma and COPD in people aged over 14 at the Hospital Clinico Universitario of Valencia (HCUV) during years 1993-1995 were reviewed. Data were analysed by entry and discharge time, sex, age and destination. Parametric survival models (exponential, Weibull and log-normal) were used for each diagnostic. Percentiles and relative percentiles were calculated; 1369 asthma emergencies and 2734 cases COPD were observed. The mean length of stay was 5.21 hours for asthma and 6.32 for COPD log-normal model was the best parametric model. Lengths of stay are greater for those hospital admitted. Stays, in cases of asthma, were shorter during months of August and November, with no differences for other variables. Also a shorter duration of stay for the month of August was found. Women are seen to stay for longer periods than men. Time modelling of emergency admission for asthma and COPD permits its use in the determining of the dates of incidence for episodes of asthma and COPD based on hospital admissions data, as seeing a median of delay in emergency rooms greater than 6 hours. For studies on air pollution impact these results imply that all those admissions during the early hours of the morning should be categorised as events of the previous day.

Adolescent↗
PubMed1999

[The patterns of use and factors associated with the patient admission of hospital emergencies for asthma and chronic obstructive pulmonary disease].

The aim of this study was to describe the epidemiological characteristics of emergencies caused by asthma and chronic obstructive pulmonary disease (COPD) at the Hospital Clínico Universitario of Valencia (Spain) and to analyze factors related to hospital admissions for the same causes. Emergency room medical records for 1993 to 1995 of patients older than 14 years of age were examined to identify those due to asthma or COPD, according to established protocol. Demographic variables were described, followed by Poisson regression analysis of time and seasonal factors affecting emergencies. Factors related to hospital admission were analyzed by logistic regression, taking into account age group, sex, place of residence, and the year, month, day and hour of emergency room arrival. Asthma patients amounted to 1% of emergencies, while COPD patients accounted for 2%. The admission rate for women with asthma was higher than for men (F/M ratio = 0.78), whereas the rate for men with COPD was higher than for women (F/M ratio = 3.14). The largest age groups with asthma emergencies included young people aged 15 to 24 years old and those over 60. Hospital admissions or transfers to other hospitals were ordered for 17.4% of asthma patients and 38.8% of COPD patients. Nearly a third of COPD patients and a fifth of asthma patients were readmitted within the ten days following the first emergency. Clear temporal patterns of COPD emergency were observed for month (most occurring in winter), day of the week (most on Monday) and hour of the day (most during daytime hours, with fewer at midday). The time patterns were less evident for asthma emergencies, although the likelihood of admission because of asthma varied by month and day of the week. Emergency room records may be useful for studying the patterns of respiratory disease presentation. Other possible uses are epidemiologic monitoring and evaluation of health care quality.

Adolescent↗
PubMed1999

Human immunodeficiency virus (HIV) infection in parenteral drug users: evolution of the epidemic over 10 years. Valencian Epidemiology and Prevention of HIV Disease Study Group.

BACKGROUND: Evaluation of acquired immunodeficiency syndrome (AIDS) prevention strategies requires an on-going follow up of the frequency of human immunodeficiency virus (HIV-1) infection. The aim of this study was to examine the trends in prevalence and incidence of HIV-1 infection among injecting drug users (IDU) during the period 1987-1996. METHODS: Transversal and cohort studies were designed which included a consecutive sample of 7132 IDU who attended three AIDS Prevention and Information Centres in the Region of Valencia (Spain) and voluntarily asked to be tested for HIV antibodies. The prevalence was estimated for each year based on the serological status of HIV-1 when the patient first visited the centre. The annual incidence rates were calculated based on the seronegative patients in which a new determination of HIV-1 was done. In order to control the possible effects on the estimations of age, sex and duration of addiction of the people studied, Poisson and logistic regression models were adjusted. RESULTS: Prevalence and incidence rates of HIV-1 infection showed parallel trends over time. The overall prevalence found was 43.6% (95% confidence intervals [CI]: 42.4-44.7%). Of the 4023 seronegative individuals, 1746 were followed up over the whole of the study period. The incidence rate observed was 6.85 x 100 persons/year (95% CI : 6.04-7.66). The prevalence figures show a decrease, which is most marked from 1990 onwards and then they tend to stabilize over the past few years. The incidence rates increase slightly up to 1991 (9.8 x 100 persons/year), and then begin to decrease. CONCLUSION: Trends of prevalence of HIV-1 infection approximate trends of subjacent incidence rate. Despite decrease in HIV-1 infection frequency observed over 10 years, both the prevalence and incidence figures continue to be high in absolute terms. It is necessary to intensify and adapt preventive measures to each subgroup at risk of infection and in the case of heterosexual transmission ensure that the failure observed in the case of IDU is not repeated.

Acquired Immunodeficiency Syndrome↗