Barriers to health care services for migrants living with HIV in Spain.

Background: In Spain, migrants are disproportionately affected by HIV and experience high rates of late diagnosis. We investigated barriers to health care access among migrants living with HIV (MLWH) in Spain. Methods: Cross sectional electronic survey of 765 adult HIV-positive migrants recruited within 18 health care settings between July 2013 and July 2015. We collected epidemiological, demographic, behavioral and clinical data. We estimated the prevalence and risk factors of self-reported barriers to health care using multivariable logistic regression. Results: Of those surveyed, 672 (88%) had information on health care access barriers: 23% were women, 63% from Latin America and Caribbean, 14% from Sub-Saharan Africa and 15% had an irregular immigration status. Men were more likely to report barriers than women (24% vs. 14%, P = 0.009). The main barriers were: lengthy waiting times for an appointment (9%) or in the clinic (7%) and lack of a health card (7%). Having an irregular immigration status was a risk factor for experiencing barriers for both men (OR: (4.0 [95%CI: 2.2-7.2]) and women (OR: 10.5 [95%CI: 3.1-34.8]). Men who experienced racial stigma (OR: 3.1 [95%CI: 1.9-5.1]) or food insecurity (OR: 2.1 [95%CI: 1.2-3.4]) were more likely to report barriers. Women who delayed treatment due to medication costs (6.3 [95%CI: 1.3-30.8]) or had a university degree (OR: 5.8 [95%CI: 1.3-25.1]) were more likely to report barriers. Conclusion: Health care barriers were present in one in five5 MLWH, were more common in men and were associated to legal entitlement to access care, perceived stigma and financial constraints.

Sexually Transmitted Infections: Experience in a Multidisciplinary Clinic in a Tertiary Hospital (2010-2013).

INTRODUCTION: The number of consultations for sexually transmitted infections (STIs) is increasing in Spain. The aim of this study was to describe and analyze the epidemiological, behavioral, clinical, and microbiological characteristics of patients registered at the STI unit of a tertiary hospital. METHODS: This was a retrospective, single-center descriptive study carried out between 2010 and 2013 in a multidisciplinary unit specialized in STIs, situated in a tertiary hospital. Epidemiological, clinical, and behavioral data were gathered using a face-to-face interview and a standardized questionnaire. Samples were collected for microbiology analysis. RESULTS: The study included 546 patients: 96% were men, 41% had human immunodeficiency virus (HIV) infection, and 56% were men who have sex with men. The reasons for consultation were the following: urethritis; genital, anal, or perianal ulcers; proctitis; oral ulcers; sexual contact with a person with a known STI; and high-risk sexual contact. The most common microbiological diagnoses were Neisseria gonorrhoeae in urethritis, Treponema pallidum in genital and anal or perianal ulcers, and Chlamydia trachomatis lymphogranuloma venereum serovars in proctitis. The highest prevalences of the main STIs studied occurred in homosexual men with HIV infection. CONCLUSION: This study confirms the increase in the incidence of STIs in recent years and the epidemiological characteristics of the HIV/STI epidemic in Spain.

Lymphogranuloma venereum in Barcelona, 2007-2012: the role of seroadaptation in men who have sex with men.

This study describes the incidence rate of reported lymphogranuloma venereum (LGV) in men who have sex with men (MSM) in Barcelona from 2007 to 2012. Epidemiological, clinical and sexual behaviour characteristics of LGV cases are described. Seroadaptive behaviours as a transmission risk factor were assessed by a telephone questionnaire during 2012. Data were handled on a strictly confidential basis. LGV annual rate ratios in MSM were compared with cases from 2007. Differences were statistically analysed with a Poisson test. The incidence rate of LGV in MSM aged 15-69 years ranged from 32·1/105 MSM per year in 2007 to 182·7/105 MSM per year in 2012. In 2012, 31/51 LGV cases (61%) answered the telephone questionnaire, of which 84% (26/31) were HIV positive, 39% (12/31) reported having sex according to their partners' serostatus and 7% (2/31) used strategic positioning. The incidence of LGV has increased since 2007 and mainly affects HIV-positive MSM. It is probable that seroadaptation has facilitated LGV transmission.

Increase in gonorrhoea among very young adolescents, Catalonia, Spain, January 2012 to June 2013.

Between January 2012 and June 2013, 27 sexually transmitted infections were reported in adolescents aged 13-15 years in Catalonia, Spain. In the first half of 2013, there were nine cases of gonorrhoea, while in the same period of 2012, there was one. In June 2013, two gonorrhoea cases aged 13-14 years, linked to a common source through a social network, were reported. The public health response should be adapted to this vulnerable population.

Lymphogranuloma venereum: a hidden emerging problem, Barcelona, 2011.

From the beginning of 2007 until the end of 2011, 146 cases of lymphogranuloma venereum (LGV) were notified to the Barcelona Public Health Agency. Some 49% of them were diagnosed and reported in 2011, mainly in men who have sex with men. Almost half of them, 32 cases, were reported between July and September. This cluster represents the largest since 2004. This article presents the ongoing outbreak of LGV in Barcelona.

Recent trends in sexually transmitted infections among adolescents, Catalonia, Spain, 2012-2017.

Monitoring sexually transmitted infections (STIs) in adolescents is essential to inform STI prevention strategies at primary and secondary levels in this key population. We aim to describe recent trends in STIs among adolescents and to analyse their socio-demographic and behavioural characteristics in Catalonia, Spain between 2012 and 2017. Data on Chlamydia trachomatis (CT) infection, gonorrhoea and syphilis cases aged from 13 to 19 years reported to the Catalan Mandatory Notifiable System from 2012 to 2017 were analysed. Diagnosis rates were calculated and a descriptive analysis was performed. Between 2012 and 2017, CT infection, gonorrhoea and syphilis cases reported among adolescents aged 13-19 years accounted for more than one-eleventh of all reported cases in Catalonia. The rate of the three nationally-notifiable STIs increased dramatically among adolescents. CT infection rates rose from 13 to 144.1 per 100,000 adolescents between 2012 and 2017, an increase of 1007%; gonorrhoea cases increased by 246% (from 13.4 to 45.4/100,000) and syphilis cases increased by 247% (from 1.7 to 5.9/100,000). Gonorrhoea and syphilis cases affected mainly males while CT infection cases were mostly in females (84%). Adolescents are being increasingly affected by CT infection, gonorrhoea and syphilis. A broader array of intervention strategies aimed at adolescents should be reinforced through strong prevention campaigns, improved sexual health information, as well as encouragement of regular offers of STI screening by healthcare providers.

Evaluating the impact of methadone maintenance programmes on mortality due to overdose and aids in a cohort of heroin users in Spain.

AIMS: To assess the relationship between methadone treatment (MT) and overdose and HIV/AIDS mortality among heroin users resident in Barcelona city. DESIGN: All patients who started treatment in any treatment centre between 1992 and 1997 were included in a cohort the first time they were admitted for heroin addiction treatment. Follow-up controls were carried out every 9 months, on average, until 31 December 1999. Variables, both constant and varying over time, were fitted into Cox regression models. FINDINGS: The study recruited 5049 patients, which provided 23,048.2 person-years. Fifty per cent were in MT during the study period; of the total cohort 1005 patients died: 38.4% due to AIDS, 34.7% to overdose and 27% to other causes. Overall mortality decreased from 5.9 deaths per 100 person-years in 1992 to 1.6 in 1999. Globally, life expectancy at birth was 39 years, 38 years lower than that of the general population. The main factor for overdose mortality was not being in MT at the time of death [relative ratio (RR) = 7.1]; other factors were being a current injector at baseline and being HIV positive. For AIDS mortality, the main factor was the calendar year (RR for 1996 versus 1999 = 4.6), the next major factor was more than 10 years of heroin consumption, followed by not being in MT, being unemployed, then having a prison record. CONCLUSIONS: The observed mortality decline could be linked to the effectiveness of low-threshold MT. The life expectancy of heroin users increased by 21 years during the study period.

The influence of intravenous drug use and HIV infection in the transmission of tuberculosis.

OBJECTIVE: To investigate whether smear-positive pulmonary tuberculosis (TB) patients present a different risk of TB transmission according to their HIV status, in an area where the majority of HIV-infected patients studied were intravenous drug users (IVDU). METHODS: A case-control study was performed on smear-positive pulmonary TB patients diagnosed between 1990 and 1993 for whom a contact study had been performed. Patients with and without HIV infection were matched by age (+/- 3 years), sex and hospital of diagnosis. A micro-epidemic was defined if two or more secondary cases were detected from the same index case. Data were analysed comparing the percentage of contacts with TB in both groups. RESULTS: Thirty-six secondary cases were detected in 436 contacts of 124 HIV-infected TB patients, whereas only 24 were identified in 624 contacts of 124 HIV-seronegative TB patients [odds ratio (OR), 2.14; 95% confidence interval (CI), 1.22-3.77; P = 0.004]. Comparing the contacts of HIV-infected patients, 34 secondary cases of TB were detected in 371 contacts of 97 IVDU, whereas only two cases were detected in 85 contacts of 27 non-IVDU (OR, 4.19; 95% CI, 1.09-15.95). HIV-seropositive index cases were observed to cause more micro-epidemics than seronegative cases (eight versus four), indicating that micro-epidemic cases were more frequent in the contacts of HIV-infected subjects (27 out of 36 versus 10 out of 24; OR, 1.41; 95% CI, 1.41-12.49; P = 0.009). All index cases in eight micro-epidemics were HIV-seropositive IVDU, whereas only four micro-epidemics were generated by HIV-seronegative subjects, none of whom were IVDU. CONCLUSIONS: Smear-positive pulmonary TB patients were more likely to transmit TB if they were HIV-infected, as evidenced by the role of IVDU in generating micro-epidemics.

CD4+ lymphocytes and tuberculin skin test as survival predictors in pulmonary tuberculosis HIV-infected patients.

BACKGROUND: We analyse whether the tuberculin skin test is a good survival marker in a cohort of pulmonary tuberculosis patients with HIV infection (PTB/HIV). In all, 494 PTB/HIV patients were enrolled in Barcelona (Spain) between January 1992 and December 1994 in the Tuberculosis Program of Barcelona. The main data problem was the large proportion of missing values in the covariates percentage of T CD4+ lymphocytes and the tuberculin test results: only 157 patients (31.8%) had both covariates recorded. METHODS: Patients were dichotomized into two groups according to their level of immunosuppression (< or = 14 and >14% T CD4+ cells). First, we carried out the semiparametric and parametric complete case analysis. After this, we analysed the data assuming a missing at random non-response pattern. We developed a bootstrap approach where missing data in the markers are imputed via a two-way linear model. Using Weibull regression estimation, we used a multiple imputation scheme to estimate the parameters of interest. RESULTS: We found significative differences for the most immunosuppressed group when comparing positive tuberculin patients with those who were tuberculin negative. From a complete case approach and through a multivariate Cox analysis, we obtained a significant relative hazard of 0.3657 (95% CI: 0.13-1.02; P = 0.054). When a Weibull model was fitted, we estimated a constant relative percentile value of pR = 4.1329 (95% CI: 0.97-17.59). From a missing data approach, we obtain a higher constant relative percentile 5.48 (P = 0.079). CONCLUSIONS: The imputation method allows us to assess the protective character of positivity for the tuberculin test for the lowest CD4+ level. These findings strongly suggest the value of the tuberculin skin test as a qualitative measure of the immunological response and its interest for developing countries where specific laboratory tests are not affordable.

Factors predicting non-completion of tuberculosis treatment among HIV-infected patients in Barcelona (1987-1996).

OBJECTIVE: To determine the predictive factors of non-completion of tuberculosis (TB) treatment among patients infected with the human immunodeficiency virus (HIV). DESIGN: Between 1987 and 1996, 2201 HIV-infected TB patients were detected by the Barcelona Tuberculosis Prevention and Control Programme. Patients who completed treatment were compared to those who abandoned. Bivariate analysis was made by chi(2) test to compare qualitative variables. Associations were measured by means of odds ratios (OR) with 95% confidence intervals (CI). Variables showing a statistically significant association were analysed at multivariate level by means of a logistic regression model. RESULTS: Treatment was carried to completion by 1065 patients (48.4%), 289 (13.1%) abandoned, 648 (29.5%) died during treatment, and 142 (6.5%) moved out of the city. Final outcome could not be established in 57 (2.5%). Intravenous drug users (IDU) represented 76.2% of patients. The rate of non-completion between 1987 and 1992 was 26.3% and for 1993-1996 it was 15.1%, a decrease of 42.6%. Living in neighbourhoods of a low socio-economic level (OR 1.61; 95% CI 1.222.13), homelessness (OR 3.56; 95% CI 2.01-6.31), history of TB (OR 1.61; 95% CI 1.12-2.33), and having presented with a current TB episode in 1987-1992 (OR 1.42; 95% CI 1.01-2.00), were risk factors for abandoning TB treatment. CONCLUSIONS: Social and health factors together influence non-completion of TB treatment in HIV-infected patients, while health interventions can improve treatment completion.

Influence of highly active anti-retroviral therapy (HAART) on the natural history of extra-pulmonary tuberculosis in HIV patients.

OBJECTIVE: To determine factors related to survival in acquired immune-deficiency syndrome (AIDS) patients with extra-pulmonary tuberculosis (EPTB), when this condition is the first AIDS-defining disease. DESIGN: A retrospective cohort-study of 549 AIDS patients with EPTB as the first AIDS-defining disease. Potential candidates to predict survival were sex, human immunodeficiency virus (HIV) exposure, the coexistence of pulmonary and EPTB at diagnosis, tuberculin skin test, directly observed therapy for tuberculosis (DOT), and highly active anti-retroviral therapy (HAART). The Kaplan-Meier method and Cox regression models were used to assess factors associated with survival. RESULTS: Estimated 3-year survival was 47.0% for those diagnosed before 1993, 72.6% for patients with first AIDS diagnosis during 1995-1996 and 84.6% for those diagnosed after 1996. A negative tuberculin test (hazard ratio [HR] = 1.6, 95% CI 1.1-2.3), not being on DOT (HR 2.2; 95% CI 1.3-3.7) and having pulmonary tuberculosis involvement also (HR 1.3; 95% CI 1.1-1.7) were independently associated with poorer survival. The survival of patients significantly improved after the introduction of HAART (HR 0.4; 95% CI 0.2-0.6). CONCLUSION: The survival of HIV patients with EPTB as their first AIDS-defining disease has substantially improved during the last decade. A negative tuberculin skin test and not receiving DOT are associated with poorer survival among HIV-infected patients whose first AIDS-defining disease is EPTB.

Effectiveness of tuberculosis control programmes in prisons, Barcelona 1987-2000.

SETTING: Different bodies have emphasised the need for prisons to implement and evaluate their own tuberculosis prevention and control programmes (TPCP), with the aims of evaluating TPCP in Barcelona prisons and obtaining conclusions that would allow any necessary modifications to be introduced to improve their effectiveness. METHODS: An assessment was carried out for the period 1987-2000, using the exhaustive retrospective method. The quantitative indicators used were defined in the same way as those employed by the Barcelona TPCP, which were taken as the gold standard. The assessment studied trends in the indicators and evaluated the impact by comparing the results with the gold standard. RESULTS: Statistically significant trends (P < 0.0001) were found for incidence rates, infection prevalence, treatment adherence rates among smear-positive cases and percentage of cases on directly observed treatment (DOT). When impact was assessed, only the decline in the average annual incidence rate (25.2%) and desired rates of adherence among smear-positives (> or = 95% since 1993) achieved the proposed objectives. CONCLUSIONS: The observed decline in incidence shows that when programmes are based on reducing diagnostic delay, controlling adherence using DOT and tracing contacts, tuberculosis control among the prisons is effective.

Characteristics of tuberculosis patients who generate secondary cases.

OBJECTIVE: To determine the characteristics of smear positive tuberculosis (TB) patients who generate secondary TB cases. METHODS: Those smear positive TB patients detected by the Barcelona Tuberculosis Program between 1990-1993, and for whom contact studies had been performed, were studied. We analyzed the predictive role of the variables: age, sex, intravenous drug use (IVDU), the presence of the acquired immune deficiency syndrome (AIDS), human immunodeficiency virus (HIV) infection, radiology pattern, district of residence, history of imprisonment, alcoholism, smoking, history of TB, treatment compliance and the number of secondary cases generated. Statistical analysis was based on the logistic regression model, calculating the odds ratios (OR) with 95% confidence intervals (CI). RESULTS: Of the 1079 patients studied, 78 (7.2%) had generated only one secondary case, and 30 (2.8%) two or more. The variables associated with generating two or more secondary cases were: IVDU (P < 0.001; OR = 4.06; CI: 1.80-9.15), cavitary radiology pattern (P = 0.002; OR = 3.69; CI: 1.62-8.43), and age (P = 0.016; OR = 0.98; CI: 0.96-0.99). When we examined those who had generated one or more secondary cases, the following variables were significant: IVDU (P = 0.043; OR = 1.75; CI: 1.02-3.02), cavitary radiology pattern (P < 0.001; OR = 3.07; CI: 1.98-4.77) and age (P < 0.001; OR = 0.98; CI: 0.97-0.99). CONCLUSION: The study of the contacts of smear positive TB patients allows us to detect an important number of secondary cases. Young adults, those with cavitary radiology pattern, and IVDU are more likely to generate secondary cases.

Proposing indicators for evaluation of tuberculosis control programmes in large cities based on the experience of Barcelona.

OBJECTIVE: To evaluate the effectiveness of the Barcelona Tuberculosis (TB) Control Programme and to propose evaluation indicators. MATERIALS AND METHODS: Using quantitative indicators, the results and impact of the programme over the period 1987 to 1999 were evaluated. Statistical analysis was based on a description of indicators, including tests for trends, and on the evolution of the incidence. RESULTS: The incidence of tuberculosis rose between 1987 and 1991 (P = 0.10), and fell between 1991 and 1999 (P < 0.001). During the study period statistically significant improvements were observed in the percentage of cases notified by the medical profession, adherence to treatment and the percentage of cases on directly observed treatment (DOT), and meningitis among children aged 0 to 4 years fell notably. However, diagnostic delay in smear-positive cases and the percentage of cases whose contacts were examined did not vary significantly. The evaluation indicated an average annual decline in tuberculosis incidence of 6.7%, and rates of adherence to treatment (94.5% among smear-positive cases) achieved their objectives. The average median diagnostic delay (36 days) and the percentage of cases with contacts examined (mean 59.8%) were rather less optimistic. CONCLUSIONS: The results of the evaluation were in general positive. Decline in incidence, meningitis in children, treatment adherence rates, diagnostic delay and percentage of cases with studied contacts were considered the best indicators for evaluation of TB programmes.

Tuberculosis screening among immigrants holding a hunger strike in churches.

SETTING: In January 2001, approximately 600 immigrants held a sit-down and hunger strike in several churches in Barcelona to force the Spanish government to comply with demands to regulate their immigration status. Following the diagnosis of a case of smear-positive pulmonary tuberculosis (TB) in one of the immigrants, we performed a large contact investigation. OBJECTIVES: To describe contact investigation procedures used in this setting and to evaluate contact investigation results. METHODS: Demographic variables were collected, and tuberculin skin tests (TST) and chest radiograph examinations were performed. Odds ratios (OR) with 95% confidence intervals (CI) were calculated and logistic regression was used for multivariate analyses. RESULTS: A total of 541 TSTs were performed. Of these, 86% were read and 40.5% yielded a positive reaction with an induration >14 mm. In a multivariate analysis, the risk of presenting a TST induration >14 mm was found to be three times higher among those aged >35 years compared to those <24 years (OR 3.40; 95%CI 1.76-6.59), and for immigrants from Bangladesh (OR 3.14; 95%CI 1.16-6.10) and Pakistan (OR 2.04; 95%CI 1.11-3.73) compared to those from India. A total of 314 chest radiographs examinations were performed and three additional cases of TB were identified, yielding a TB prevalence of 0.7%. CONCLUSIONS: By focusing efforts and conducting targeted TB screening in this high-risk population, it was possible to complete the intervention in only 3 days. A high prevalence of TB infection and TB disease was found.

[Tuberculosis trends in Barcelona (1987-1995). Impact of the human immunodeficiency virus and control measures]. / Evolución de la tuberculosis en Barcelona (1987-1995). Influencia del virus de la inmunodeficiencia humana y de las medidas de control.

BACKGROUND: To study the epidemiology to tuberculosis (TB) in Barcelona, Spain from 1987 to 1995, analyzing the influence of HIV infection and the impact of control measures. PATIENTS, MATERIAL AND METHODS: All cases detected by the Barcelona Tuberculosis Prevention and Control Program were included in the study of the evolution of TB incidence according to different variables. The impact of HIV infection was analyzed through the attributable risk per cent (AR), and control measures through the evolution of the rate of treatment compliance, contact studies, and diagnostic delay. RESULTS: We detected 8,942 patients, 23.2% of whom were found through the active epidemiological surveillance system, representing an average annual incidence of 60.4/100,000. The incidence peaked in 1991 (68.7/100,000) and slowly declined to 55.7/100,000 in 1995. Men showed higher incidence (RR: 2.74; CI 95%: 2.62-2.87), particularly among the young (25-34 years olds), 53.3% of whom were HIV (+). The AR for HIV was 92.7%. In this period there was an increase in TB HIV (+), IVDU, and prisoners. Treatment compliance (80.8% in 1987 to 93.8% in 1995) and contact studies (3.2 studies/case in 1995) evolved favorably, unlike but diagnostic delay (35 days in 1995) did not. CONCLUSIONS: The Active Epidemiological Surveillance System has affored us a clear view of the actual situation regarding TB in Barcelona, Spain. Despite the HIV epidemics and the high number of IVDU, the evolution of TB has shown a steady decline due to improvement in control measures.

[The evolution of AIDS mortality and survival in Barcelona (1981-1997)]. / Evolución de la mortalidad y supervivencia del SIDA en Barcelona (1981-1997).

BACKGROUND: To analyze the evolution of AIDS mortality and survival in Barcelona, Spain. PATIENTS AND METHODS: AIDS-cases registered in Barcelona (Spain) between 1981-1997. Study of mortality and survival probability. RESULTS: Mortality decreased by 55% between 1996-1997. Survival probability at 547 days was of 80.3% in 1997 compared with 48.6% before 1988. Being older than 36 years old, IVDU, having other AIDS-defining disease than tuberculosis, and year of diagnostic before 1997 were associated with poor survival. CONCLUSIONS: AIDS mortality in Barcelona has enormously decreased. The best survival in 1997 is probably attributable to the new antiretroviral therapies.

[Evaluation of the tuberculosis control programs of the autonomous regions of Spain]. / Evaluación de los programas de control de tuberculosis de las Comunidades Autónomas de España.

BACKGROUND: After the resurgence of tuberculosis in the eighties, several institutions pushed to rapidly create tuberculosis programs and to improve the effectiveness of those in existence. The objective of this paper is to evaluate the programs of the Autonomous Communities of Spain. MATERIAL AND METHODS: A questionnaire was sent to 17 Autonomous Communities and two cities Ceuta and Melilla. A table with minimum objectives was made in order to evaluate the impact of each program. The study period was 1996. RESULTS: The percentage of answers was 100%. Fourteen Autonomous Communities (82%) confirmed they have a tuberculosis program, but with important limitations. There are 3.8 public health workers per 1,000 cases of tuberculosis. Eleven Autonomous Communities had active surveillance, but only 4 know adherence rates to tuberculosis treatments, 3 had supervised treatments, and 3 know diagnostic delays. Ten know results about the percentage of cases with revised contacts. 70% of 19 revised programs did not fulfill the recommended basic objectives. CONCLUSIONS: Tuberculosis control in Spain is not adequate for a developed country. An improvement of the programs in needed, with increase of resources and with reference support centers which would carry out annual evaluations.

[Differential characteristics of AIDS in foreign immigrants]. / Características diferenciales del sida en inmigrantes extranjeros.

BACKGROUND: AIDS in foreign migrants can have specific characteristics compared with that of Spanish patients. METHODS: Cross-sectional study, including cases from the Barcelona AIDS register diagnosed from 1988 to 1998. Global characteristics of migrants are compared with those of Spanish patients. Adjusted odds ratio (OR) with 95% confidence interval (CI) were calculated through logistic regression. A formal analysis was also performed. RESULTS: Among the 4,663 patients included, 5% were migrants. 33% of patients were diagnosed with AIDS 10 years after having migrated to Spain. They differentiate at the multivariate level by sex (OR [male]: 1.70; CI: 1.10-2.64), district of residence (OR [district I]: 2.07, IC: 1.50-2.87) and transmission pattern (OR [other than injecting drug users]: 4.08; IC: 2.77-5.99). No significant differences in survival were showed. CONCLUSIONS: The percentage of migrants among AIDS cases in Barcelona is low. Migrants are more frequently men, more often live in the inner city and are less frequently injecting drug users.

[Imputation of the date of HIV seroconversion in cohorts of haemophiliacs]. / Imputación del instante de seroconversión al VIH en cohortes de hemofílicos.

OBJECTIVES: To describe the methods used to impute HIV seroconversion date in the haemophiliac cohorts from GEMES project and to validate its use. METHOD: 632 haemophiliacs coming from three hemophilia units identified as HIV+ and 1.092 individuals coming from 5 project GEMES cohorts with a seroconversion window (time among test HIV and HIV+) less than 3 years where mid point (PM) was assumed as seroconversion date. For both groups, seroconversion date was imputed after estimating the probability distribution of seroconversion by means of the EM algorithm. Two imputation methods are used: one obtained from the expected value and the other from the geometric mean of 5 random samples. from the estimated distribution. Imputations have been validated in the non haemophiliacs cohorts comparing with the PM seroconversion date. Also AIDS free time and survival from the different seroconversion imputed dates were compared. RESULTS: Median seroconversion date is located in May of 1993 for the non haemophiliacs and in 1982 for the haemophiliacs. Not big differences are observed among the imputed seroconversion dates and the mid-point seroconversion date in the non-haemophiliac cohorts. Similar results are found for the haemophiliac cohorts. Also no differences are observed in the estimated AIDS-free time for both groups of cohorts. CONCLUSIONS: Geometric mean imputation from several random samples provides a good estimate of the HIV seroconversion date that can be used to estimate AIDS-free time and survival in haemophiliac cohorts where seroconversion date is ignored.