A cross-sectional assessment of frailty, falls and perceptions of ageing in people living with HIV using an mHealth platform.

OBJECTIVE: To evaluate frailty, falls and perceptions of ageing among clinically stable individuals with HIV, engaged with remote healthcare delivered via a novel smartphone application. METHODS: This was a multi-centre European cross-sectional, questionnaire-based sub-study of EmERGE participants. Frailty was assessed using the five-item FRAIL scale. Present criteria were summed and categorized as follows: 0, robust; 1-2, pre-frail; 3-5, frail. Falls history and EQ-5D-5L quality of life measure were completed. Participants were asked their felt age and personal satisfaction with ageing. RESULTS: A total of 1373 participated, with a mean age of 45 (± 9.8) years. Frailty was uncommon at 2%; 12.4% fell in the previous year, 58.8% of these recurrently. Mood symptoms and pain were prevalent, at 43.3% and 31.8%, respectively. Ageing satisfaction was high at 76.4%, with 74.6% feeling younger than their chronological age; the mean felt age was 39.3 years. In multivariable analysis, mood symptoms and pain were positively associated with frailty, falls and ageing dissatisfaction. An increase in pain severity and mood symptoms were respectively associated with 34% and 63% increased odds of pre-frailty/frailty. An increment in pain symptoms was associated with a 71% increase in odds of falling. Pain was associated with ageing poorly, as were mood symptoms, with odds of dissatisfaction increasing by 34% per increment in severity. CONCLUSIONS: Although uncommon, frailty, falls and ageing dissatisfaction were seen in a younger cohort with medically stable HIV infection using a remote care model, promoting screening as advocated by European guidelines. These were more common in those with pain or mood symptoms, which should be proactively managed in clinical care and explored further in future research.

The cost of care for people living with stable HIV in Croatia and the efficiency of EmERGE.

AIM: To estimate the cost-effectiveness of the EmERGE Pathway of Care for medically stable people living with HIV (PLHIV) at the University Hospital for Infectious Diseases (UHID), Zagreb. The Pathway includes a mobile application enabling individuals to communicate with their caregivers. METHODS: This study involving 293 participants collected data on the use of HIV outpatient services one year before and after EmERGE implementation. In departments supporting HIV outpatients, a micro-costing exercise was performed to calculate unit costs. These were combined with mean use of HIV services per patient year (MPPY) to estimate average annual costs. Primary outcomes were CD4 count, viral load, and secondary outcomes were patient activation, PAM13; and quality of life, PROQOL-HIV. Information on out-of-pocket expenditures was also collected. RESULTS: Outpatient visits decreased by 17%, from 4.0 (95% CI 3.8-4.3) to 3.3 MPPY (95% CI 3.1-3.5). Tests, including CD4 count, decreased, all contributing to a 33% reduction of annual costs: 7139 HRK (95% CI 6766-7528) to 4781 HRK (95% CI 4504-5072). Annual costs including anti-retroviral drugs (ARVs) decreased by 5%: 43101 HRK (95% CI 42728-43,490) to 40 743 HRK (95% CI 40466-41,034). ARVs remain the main cost driver in stable PLHIV. Primary and secondary outcomes did not change substantially between periods. CONCLUSION: EmERGE Pathway was a cost-saving intervention associated with changes in management, and a reduction in outpatient visits, tests, and costs. ARV costs dominated costs. Future efficiencies are possible if EmERGE is introduced to other PLHIV across the UHID and if ARV prices are reduced.

Toxicity-related antiretroviral drug treatment modifications in individuals starting therapy: a cohort analysis of time patterns, sex, and other risk factors.

BACKGROUND: Modifications to combination antiretroviral drug therapy (CART) regimens can occur for a number of reasons, including adverse drug effects. We investigated the frequency of and reasons for antiretroviral drug modifications (ADM) during the first 3 years after initiation of CART, in a closed cohort of CART-naïve adult patients who started treatment in the period 1998-2007 in Croatia. MATERIAL AND METHODS: We calculated differential toxicity rates by the Poisson method. In multivariable analysis, we used a discrete-time regression model for repeated events for the outcome of modification due to drug toxicity. RESULTS: Of 321 patients who started CART, median age was 40 years, 19% were women, baseline CD4 was <200 cells/mm3 in 71%, and viral load was ≥100 000 copies/mL in 69%. Overall, 220 (68.5%) patients had an ADM; 124 (56%) of these had ≥1 ADM for toxicity reasons. Only 12.7% of individuals starting CART in the period 1998-2002 and 39.4% in the period 2003-2007 remained on the same regimen after 3 years. The following toxicities caused ADM most often: lipoatrophy (22%), gastrointestinal symptoms (20%), and neuropathy (18%). Only 5% of drug changes were due to virologic failure. Female sex (hazard ratio [HR], 2.42 95%; confidence intervals, 1.39-4.24) and older age (HR, 1.42 per every 10 years) were associated with toxicity-related ADM in the first 3 months of a particular CART regimen, but after 3 months of CART they were not. CONCLUSIONS: Less toxic and better-tolerated HIV treatment options should be available and used more frequently in Croatia.

Incidence, risk factors, and clinical findings of syphilis among men living with HIV in Croatia during the COVID-19 pandemic.

We conducted a nationwide longitudinal observational study to estimate the incidence of syphilis in a cohort of male persons living with HIV (MLWH) in Croatia in the pre-COVID-19 and COVID-19 years. Data were reviewed and extracted from the clinical database. We analyzed 1187 MLWH (≥ 18 years) in care in Croatia from 2018 to 2021 and used Poisson regression to calculate rates. We observed a 91.4% increase in incidence between 2019 and 2020; the overall rate was 6.0/100 person-years, and the annual rate ranged from 3.3/100 person-years in 2018 to 9.3/100 person-years in 2021. We found higher rates in men who have sex with men, MLWH with a baseline history of syphilis, MLWH with a more recent HIV diagnosis, and a lower rate in those who had clinical AIDS. The rate of syphilis serological testing was 3.5% lower in 2020 compared to 2019. Recurrent syphilis was more likely asymptomatic compared to the first episodes. In conclusion, during the COVID-19 epidemic years, there was a huge increase in syphilis. Results highlight the need for enhanced and novel prevention interventions.

Hepatitis A Outbreak in Men Who Have Sex with Men Using Pre-Exposure Prophylaxis and People Living with HIV in Croatia, January to October 2022.

The hepatitis A virus (HAV) is a highly hepatotropic virus transmitted mainly via the fecal-oral route. The purpose of this study is to describe a prolonged HAV outbreak in HIV-infected men who have sex with men (MSM) and pre-exposure prophylaxis (PrEP) users in Croatia in 2022. Croatia has a centralized system of HIV care and the PrEP service is only available at the University Hospital for Infectious Diseases (UHID), Zagreb. We reviewed all MSM living with HIV and MSM PrEP users at UHID and identified those diagnosed with HAV between January and October 2022. During this period, a total of 1036 MSM living with HIV and 361 PrEP users were followed, and 45 (4.4%) and 32 (8.9%) were diagnosed with HAV, respectively. Most cases were diagnosed in mid-February. A total of 70.1% (726/1036) MSM living with HIV and 82.3% (297/361) PrEP users were susceptible to HAV. Sequencing information was available for 34 persons; in all cases the HAV subtype IA was found. Our findings indicate that both MSM living with HIV and HIV-uninfected PrEP users are vulnerable to HAV infection and might be a potential source for a more widespread HAV epidemic.

Efficiency of the EmERGE Pathway of Care in Five European HIV Centres.

OBJECTIVE: We aimed to calculate the efficiency of the EmERGE Pathway of Care in five European HIV clinics, developed and implemented for medically stable people living with HIV. METHODS: Participants were followed up for 1 year before and after implementation of EmERGE, between April 2016 and October 2019. Micro-costing studies were performed in the outpatient services of the clinics. Unit costs for outpatient services were calculated in national currencies and converted to US$ 2018 OECD purchasing parity prices to enable between clinic comparisons in terms of outcomes and costs. Unit costs were linked to the mean use of services for medically stable people living with HIV,  before and after implementation of EmERGE. Primary outcome measures were CD4 count and viral load; secondary outcomes were patient activation (PAM13) and quality of life (PROQOL-HIV). Out-of-pocket expenditure data were collected. RESULTS: There were 2251 participants: 87-93% were male, mean age at entry was 41-47 years. Medically stable people living with HIV had outpatient visits in four sites which decreased by 9-31% and costs by 5-33%; visits and costs increased by 8% in one site, which had to revert back to face-to-face visits. Antiretroviral drugs comprised 83-91% of annual costs: the Portuguese site had the highest antiretroviral drug costs in US$ purchasing parity prices. Primary and secondary outcome measures of participants did not change during the study. CONCLUSIONS: EmERGE is acceptable and provided cost savings in different socio-economic settings. Antiretroviral drug costs remain the main cost drivers in medically stable people living with HIV. While antiretroviral drug prices in local currencies did not differ that much between countries, conversion to US$ purchasing parity prices revealed antiretroviral drugs were more expensive in the least wealthy countries. This needs to be taken into consideration when countries negotiate drug prices with pharmaceutical vendors. Greater efficiencies can be anticipated by extending the use of the EmERGE Pathway to people with complex HIV infection or other chronic diseases. Extending such use should be systematically monitored, implementation should be evaluated and funding should be provided to monitor and evaluate future changes in service provision.

Timeliness of antiretroviral therapy initiation in the era before universal treatment.

We assessed the prevalence and factors related to the time to antiretroviral (ART) initiation among persons who entered HIV care and subsequently started ART in Croatia from 2005 to 2014. Included were patients ≥ 18 years, the follow-up ended on Dec/31/2017. 628 patients were included into the study 91.9% were men; median age was 36.1 (Q1-Q3: 29.6-43.8) years. Rapid (within 7 days of diagnosis) ART initiation was observed in 21.8% patients, 49.8% initiated ART within 30 days, 21.7% and 28.5% had intermediate (31 days-1 year) and late initiation (> 1 year), respectively. Of 608 patients that achieved an undetectable viral load, 94% had a plasma HIV-1 RNA < 50 copies/ml at last measurement after a median follow-up of 5.2 years. On quantile regression analysis, calendar year of entry into care, and markers of more advanced HIV disease (higher viral load, lower CD4 cell count and clinical AIDS) were significantly associated with earlier ART initiation. Early ART was not related to a gap in care afterwards at all quantiles. In conclusion, a significant proportion of patients started ART early in Croatia in 2005-2014. Early ART initiation led to durable viral load suppression and was not associated with a subsequent gap in care.

A rare case of Fitz-Hugh-Curtis syndrome caused by Chlamydia trachomatis in an HIV-positive male patient.

Fitz-Hugh-Curtis syndrome, a rare complication of pelvic inflammatory disease, is an inflammation of the liver capsule (thus called perihepatitis) and the surrounding peritoneum. It occurs extremely rarely in men and is typically characterized by a sudden onset of severe pain in the right upper abdominal quadrant. Ultrasound examination of the liver does not reveal any morphologic changes, and liver function tests are usually normal. Computerized tomography shows the thickening of the perihepatic fat, but definitive diagnosis is only possible by direct visualization by laparoscopy or laparotomy. We present a 33-year-old HIV-positive man with Chlamydia trachomatis proctitis who developed severe right upper abdominal quadrant pain. Abdominal ultrasound did not show any liver pathology, while computerized tomography revealed hepatic capsular thickening. After 21 days of doxycycline therapy, the patient's symptoms subsided. Based on the clinical presentation and liver computerized tomography examination, the diagnosis of proctitis and the resulting Fitz-Hugh-Curtis syndrome was made. Although it is rarely seen in male patients, it should be a part of differential diagnosis in patients who present with right upper abdominal quadrant pain, especially in men who have sex with other men.

Genital Herpes Zoster as Possible Indicator of HIV Infection.

Herpes zoster (HZ) is an acute, cutaneous viral infection caused by the reactivation of varicella-zoster virus (VZV) (1). It is a frequent medical condition with an incidence rate of 2-3 cases per 1000 person/years in the general population and 7-10 cases per 1000 person/years after the age of 50 (1,2). Risk factors and triggers for reactivation of HZV have not yet been determined precisely, but are likely to include malignancies, immune deficiencies, solid organ and bone marrow transplant recipients, autoimmune diseases, psychological conditions, emotional stress, human immunodeficiency virus (HIV) infection, and other patients receiving immunosuppressive therapies (1,3). A 24-year-old IV drug user presented with grouped clusters of vesicles and erosions on an erythematous, edematous base distributed on the left side of the penile shaft and the left infraumbilical region (Figure 1, a and b), with regional lymphadenopathy. He had prodromal symptoms of pain, dysesthesia and burning a few days prior to the appearance of the skin lesion. The patient reported unprotected sexual contacts a few months before the eruptions. The unilateral distribution was highly suggestive of herpes zoster. A Tzanck smear was performed by obtaining scrapings from the base of a fresh vesicular lesion after it had been unroofed; it showed the characteristic presence of multinucleated giant cells that suggested herpes infection. Polymerase chain reaction (PCR) analysis of vesicular fluid yielded positive results for VZV. A 7-day course of acyclovir (800 mg 5 times a day) was initiated. The patient reported marked improvement on the second day of antiviral therapy. The course was uncomplicated, and the lesions healed without postherpetic neuralgia. Serologic tests for syphilis (VDRL/RPR and TPHA) and hepatitis C and B serologic tests were negative, but HIV test (enzyme immunoassays (EIA) for HIV-1 and HIV-2 antibodies were positive, which was later confirmed with Western blot (WB) tests. Because of the positive HIV test, the patient was referred to the Clinic for Infectious Diseases for further treatment. Herpes zoster is painful vesicular skin eruption with unilateral dermatomal involvement, usually with a severe impact on the quality of life in affected patients (1). The risk for developing HZ during a lifetime in patients exposed to VZV infection is 10-30% (4). However, the risk is higher in immunocompromised patients, particularly in cancer patients and HIV-positive patients (1,5,6). HZ is seen approximately 7 times more frequent in patients with HIV infection (5). Reactivated VZV infection may occur at any stage of HIV infection and may be the first clinical evidence of HIV infection. The development of HZ in immunocompromised individuals can be explain by decline in cell-mediated immunity and CD4 count (6). HZ predominantly affects the thoracic region, followed by the head, cervical, and lumbar regions (1). Sacral dermatomes are involved in only up to 2% of cases (1). HZ involving the penis is rarely reported, with only few case reports in the literature (3,7-9). Birch et al. compared VZV and herpes simplex virus (HSV) in specimens obtained from the genital lesions of adults presenting with presumed genital herpes infection (10). They found VZV in nearly 3% of virus-positive genital specimens, which demonstrates that this virus needs to be considered in the differential diagnosis of genital herpetic lesions (10) and that it is possible that genital HZ infection is underdiagnosed. Tzanck smear is a rapid and inexpensive method, but it cannot differentiate VZV from HSV. Genital HZ could be mistaken for zosteriform HSV infection, so a PCR test should be performed to confirm the underlying diagnosis (1). Genital forms of HZ are rare and sometimes clinically difficult to diagnose, especially when the typical zosteriform distribution is lacking; PCR testing is therefore suggested. HZ is considered a possible HIV indicator; an HIV test should therefore be performed. According to our knowledge and literature search, this is the first case report of penile HZ in an HIV-positive patient.

Successful treatment of genotype 3 hepatitis C infection in a noncirrhotic HIV infected patient on chronic dialysis with the combination of sofosbuvir and velpatasvir: A case report.

RATIONALE: Data on anti-HCV therapy in patients on dialysis is still evolving. Sofosbuvir is mainly eliminated through the renal route and there is controversy about its use in these patients. PATIENT CONCERNS: We describe a 53-year-old male patient with HCV genotype 3 and human immunodeficiency type 1 (HIV) infection on chronic dialysis. HIV infection was diagnosed in 1987 and since July 2007 the patient was compliant with his antiretroviral therapy (ART) and had an undetectable plasma HIV viral load on all follow-up measurements. The patient was known to have HCV infection since 1997 but has never been treated for chronic hepatitis C. Because of progressive renal impairment dialysis started in 2005. DIAGNOSIS: Before anti-HCV treatment commenced the patient liver transient elastography (FibroScan) indicated F3 fibrosis (stiffness, 11.6 kPa) and his HCV RNA viral load was 320,798 IU/mL (Abbott RealTime HCV assay). INTERVENTION: Fixed dose combination of sofosbuvir/velpatasvir (400 mg/100 mg) for 11 weeks. OUTCOMES: Twelve weeks after treatment cessation HCV RNA was undetectable, hence the patient achieved a sustained virologic response. The drugs were well tolerated and the patient did not report any side effects. LESSONS: Sofosbuvir/velpatasvir may be an option for HCV genotype 3 infection in patients coinfected with HIV on long-term dialysis.

Cardiovascular markers of inflammation and serum lipid levels in HIV-infected patients with undetectable viremia.

Patients successfully treated for HIV infection still have an increased risk for cardiovascular morbidity and mortality, which might be related not only to traditional risks, but also to inflammation and dyslipidemia. We examined the relationship of serum lipid levels with plasma biomarkers of inflammation using a composite inflammatory burden score (IBS) based on individual (>75th percentile) measurements from the following seven markers: CD40L, tPA, MCP-1, IL-8, IL-6, hCRP and P-selectin. IBS was categorized as 0 (none of the biomarkers >75th percentile), 1, 2 and 3 or more scores. Correlations between the IBS and lipid parameters were examined by ordered logistic regression proportional odds models to estimate the odds of more elevated biomarkers. 181 male patients with undetectable HIV-viremia were included into the study. In the multivariate model, a one-unit increase (mmol/L) of total cholesterol and triglycerides was associated with a 1.41-fold (95% CI, 1.13-1.76) and 1.37-fold (95% CI, 1.18-1.60) increased odds of having a greater IBS, respectively. Those with an IBS score ≥1 compared to none had 2.14 (95% CI, 1.43-3.20) higher odds of having a one-unit increased total cholesterol/HDL-cholesterol ratio. In successfully treated HIV-infected persons dyslipidemia was associated with inflammation.

The role of Chlamydia trachomatis in prostatitis syndrome--our experience in diagnosis and treatment.

Since the beginning of 1999, over 1500 patients with symptoms of chronic prostatitis were examined at Dr. Fran Mihaljevic University Hospital for Infectious Diseases in Zagreb. In almost all of these patients urethral swabs and quantitative segmented bacteriologic cultures and microscopy of expressed prostatic secretion (EPS) or voided bladder urine3 (VB3) were performed as described by Meares and Stamey. Urethral swabs, EPS or VB3 were examined for the presence of Chlamydia (C.) trachomatis by McCoy culture and Lugol stain or by immunofluorescent typing with monoclonal antibodies. In the majority of patients C. trachomatis was demonstrated in parallel in EPS or VB3 by DNA/RNA hybridization method. Normal white blood cell count viewed per high power field<10 was found in 362 (68%) of 536 patients with symptoms of chronic prostatitis and C. trachomatis detected in EPS or VB3. These findings additionally suggest that C. trachomatis can be suspected as a causative pathogen in all categories of chronic prostatitis syndrome. Furthermore, this paper summarizes the results of five previously published clinical studies on the efficacy and tolerability of various treatment schemes for chronic chlamydial prostatitis, conducted from the beginning of 1999 until the end of 2003.

Etiology of chronic prostatitis syndrome in patients treated at the university hospital for infectious diseases "Dr. Fran Mihaljevic" from 2003 to 2005.

A total of 835 patients with symptoms of chronic prostatitis syndrome and no evidence of structural or functional lower genitourinary tract abnormalities were examined in a three year period at the Outpatient Department for Urogenital Infections, University Hospital for Infectious Diseases "Dr. Fran Mihaljevic" Zagreb, Croatia. Disease etiology was determined in 482 (57.72%) patients. Chlamydia trachomatis was proved to be the causative pathogen in 161 patients, Trichomonas vaginalis in 85, Escherichia coli in 68, Enterococcus in 51, Proteus mirabilis in 20, Klebsiella pneumoniae in 9, Streptococcus agalactiae in 15, Ureaplasma urealyticum in 49 patients with chronic prostatitis. Other patients had mixed infection. In 257 (53.32%) of 482 patients, the inflammatory finding (>10 WBCs/hpf) was found in EPS or VB3. Normal WBCs/hpf (<10) was found in 103 (63.98%) of 161 patients with symptoms of chronic prostatitis in whom C. trachomatis was detected in EPS or VB3, in 50 (58.82%) of 85 patients in whom Trichomonas vaginalis was isolated, and in 23 (46.94%) of 49 patients in whom Ureaplasma urealyticum was isolated.

The role of unusual pathogens in prostatitis syndrome.

A total of 1442 patients with symptoms of chronic prostatitis were examined over a 4-year period at the Outpatient Department for Urogenital Infections, University Hospital for Infectious Diseases "Dr. Fran Mihaljevic", Zagreb, Croatia. An infectious aetiology was determined in 1070 (74.2%) patients. In 561 of 1070 (52.4%) patients the inflammatory finding (>10 WBC/hpf) was found in expressed prostatic secretions (EPS) or voided bladder urine (VB(3)). Normal, <10 WBCs/hpf was found in 362 of 536 (67.5%) patients with symptoms of chronic prostatitis in whom Chlamydia trachomatis was detected in EPS or VB(3), in 51 of 151 (33.8%) patients with isolated Trichomonas vaginalis and in 40 of 72 (55.6%) patients with isolated Ureaplasma urealyticum. Escherichia coli was the causative pathogen in 95, Enterococcus in 68, Proteus mirabilis in 37, Klebsiella pneumoniae in 16, Streptococcus agalactiae in 19, and Pseudomonas aeruginosa in 3 patients with chronic prostatitis. Other patients had a mixed infection. In patients with chronic bacterial prostatitis (CBP) caused by E. coli, P. mirabilis, K. pneumoniae, E. or S. agalactiae, an inflammatory finding was regularly found in EPS or VB(3).

Cardiovascular markers of inflammation and serum lipid levels in HIV-infected patients with undetectable viraemia.

INTRODUCTION: Successfully treated HIV-infected patients may still have an increased risk for cardiovascular morbidity and mortality, which might be related not only to traditional risks, but also to inflammation and dyslipidemia induced by HIV and/or antiretroviral therapy [1, 2]. We examined the relationship of serum lipid levels with plasma biomarkers of inflammation using a composite inflammatory burden score (IBS) from the following seven markers of inflammation: CD40L, tPA, MCP-1, IL-8, IL-6, hCRP and P-selectin. MATERIALS AND METHODS: Subjects were selected among consecutive HIV-infected males ≥18 years of age with an undetectable viral load (<50 copies/mL of HIV1-RNA), seen at the University Hospital for Infectious Diseases, Zagreb, Croatia, in the period from January 2012 to March 2013. Plasma inflammatory biomarkers (CD40L, tPA, MCP-1, IL-8, IL-6, hCRP and P-selectin, quantified by bead-based cytometry) >75th percentile were considered elevated and an IBS was constructed as the presence of zero, one, two, or three or more elevated biomarkers. Correlations between the IBS and lipid parameters were examined using Spearman's Rho and by ordered logistic regression proportional odds model to estimate the odds of more elevated (>75th percentile) biomarkers. RESULTS: 181 male patients were included into the study, the median age was 46.7 (Q1-Q3, 39.9-55.0) years and the median current CD4 cell count was 553.0 (Q1-Q3, 389-729) per microliter. The patients were mainly treated with two nucleoside reverse transcriptase inhibitor (NRTI) plus one non-NRTI (NNRTI) (N=100, 60.8%) or two NRTI plus lopinavir (N=50, 27.6%). There was a significant correlation between the IBS and serum cholesterol (Rho=0.23, 95% CI, 0.09-0.37), triglycerides (Rho=0.30, 95% CI, 0.16-0.42) and cholesterol/HDL-cholesterol ratio (Rho=0.25, 95% CI 0.11-0.38). In the multivariable model a one unit increase in cholesterol/HDL-cholesterol ratio was associated with a 1.72-fold (95% CI, 1.27-2.33) increased odds of having a greater IBS. One unit increase (mmol/L) of cholesterol and triglycerides was associated with a 1.41-fold (95% CI, 1.13-1.76) and 1.37-fold (95% CI, 1.18-1.60) increased odds of having a greater IBS, respectively. CONCLUSIONS: Our study suggests that in virologically suppressed patients there is a significant association between markers of inflammation and serum levels of cholesterol and triglycerides as well as the cholesterol/HDL-cholesterol ratio.

Unsafe sexual behavior among HIV-infected patients in Croatia, 2006: prevalence and associated factors.

Information about risky sexual behavior among people living with HIV/AIDS is important to prevent the spread of the disease. Using an anonymous, self-administrated questionnaire, we surveyed 185 HIV-infected patients about risk behaviors at the University Hospital for Infectious Diseases in Croatia. Unprotected anal or vaginal sex in the preceding 6 months with partners of uninfected/unknown HIV status was reported by 20% of men who have sex with men (MSM), about half of whom reported multiple casual partners of unknown HIV status; 6% of heterosexual men; and 3% of women. Heterosexual patients were potentially more likely to expose regular partners to HIV but reported no risk behaviors with casual, non-concordant partners. MSM reported more risk behaviors, which were strongly associated with having > or = 2 sexual partners in the last 6 months and both insertive and receptive anal sex. Educational interventions in Croatia should target MSM to prevent high rates of HIV transmission.