The overall picture of HIV/AIDS in Vietnam continues to be worrying over time. Since the first case of HIV infection sexually transmitted in 1990 [1
], it then has spread dramatically through both risk sexual and drug use behavior across the country, with 160,019 cases reported nationwide [2
]. To date researchers and policy makers remain uncertain about further development of this epidemic as well as progression of prevention efforts. Given previous research and literature, the HIV transmission has been focused largely upon injecting drug users (IDU) and female sex workers (FSW) due to their unsafe behaviors such as sharing injecting equipment and non condom sex [1
]. However, much attention to such high-risk groups may restrict our understanding of other groups that may be also at risk of being affected by the epidemic [7
]. Several subpopulations in Vietnam such as migrants, militants, and rural communities actually have also been believed as sufferers. Studies in some developed and developing countries have identified the association of migration [9
], social contexts [12
], and deficit in HIV prevention knowledge [8
], social vulnerabilities of marginalized groups [13
], and lack of access as well as insufficient and incomprehensive approaches to HIV preventive information and programs with increased epidemic [15
Although fighting against the HIV/AIDS spread in Vietnam has become comparatively successful in several aspects, there are high risk groups that have not been engaged in HIV-related research and prevention programs. The recent data show that in Vietnam HIV cases have been reported in all 63 provinces and cities, almost 98% of districts, and more than 70% of wards, communes, and towns [2
]. This means that the HIV epidemic has affected not only high-risk groups in urban areas, but other communities, especially ethnic minority youth in rural settings due to many individual and social factors [16
In the Mekong river sub-region, the East-west Economic Corridor (EWEC) is one of the three routes with 1,600 km in length to connect the Indian and Pacific Oceans. The corridor has been built on the route that was known during the Vietnam War as "Route Number Nine" running through two mountainous districts, namely Dakrong and Huong Hoa, the very poor districts of Quang Tri province in central Vietnam. These districts have two main ethnic minorities Pahco and Vankieu, bordering with Laos through Lao Bao border gate. The completion of this route paved regional mobility and helped generate trade opportunities as well as facilitate cultural exchange for the region, especially between Laos, Thailand and Vietnam. The development of road infrastructure in rural residential areas has led to an increase in trade and accessibility and has therefore spurred economic and social development. Local people are increasingly able to access previously inaccessible services and trade opportunities. The development of routes, however, has influenced the social habits of affected communities in unexpected ways such as prostitution, drug use, sexual abuse and harassment and others. Many of these changes have the potential to negatively affect public health, especially by increasing unprotected groups' risks of contracting HIV and sexually transmitted diseases (STDs). In the previous baseline survey of the project "Building a community-based pilot model for preventing HIV/AIDS in two mountainous districts of Quang Tri province"
, it was found that in parallel with the process of migration the facilitators and risk factors that increased transmitting HIV included changed lifestyles, social norms in favor of pre-marriage sex, local tradition "di sim" for seeking sex partners, non-condom sex due to limited perceptions of preventing HIV as well as lack of access to HIV prevention services [17
]. Using the results of that survey, we implemented a variety of PCC that aimed to promote perceptional and behavioral change for preventing HIV among ethnic minority youth of some communes in Dakrong district of Quang Tri province.
In evaluating the impact of a communication campaign, program officers and researchers would like to be able to estimate the effect of intervention that is designed to change a behavior. It has been well recognized among researchers and evaluators that calculating effectiveness is the most important part, but is sometimes the most challenging [18
]. One can not claim a particular amount of behavior change without a causal attribution. A causal inference must be reached that attributes the net change in behavior to exposure to the intervention and not to other impacts or, worse yet, to changes that occurred before the intervention was implemented. Because in this study we launched the intervention across the villages of two communes Dakrong and Ango and because residents including respondents were highly mobile between intervention and control villages, it is a difficult task for researchers to design a randomized control group study.
The objective of this study was to estimate the relatively net effect of participatory community communications (PCC) on ideational and behavioral change for HIV prevention among ethnic minority youth in a mountainous district in central Vietnam using propensity score matching (PSM).
From literature PSM is highly recommended as it is one of the strong statistical techniques [18
]. This method can help reduce selection bias as it allows for quasi-experimental contrasts between subjects receiving "treatment" and those in "control" groups based on their observed characteristics. Proper use of PSM should also allow for rigorously derived and relatively unbiased estimates of communication effects on participants' behavior [21
]. Because of its ability to reduce selection bias, PSM has become increasingly used in the fields of education [22
], communication [20
], medicine and epidemiology [23
], policy evaluation [24
], economics [25
], and psychology [26
]. Although commonly applied in diverse disciplines in various settings, too little has been achieved in measuring the effect of PCC on HIV preventive behavior among ethnic minority youth in marginalized areas of developing countries like Vietnam.
A theoretical framework for this study was based on a comprehensive conceptual model by Kincaid [19
] (Figure ) that has been adapted from a wide range of literature resources. Under this theory, the psychological influences including knowledge, attitude, social norm, intention, self-efficacy, and others can be combined as ideation. Specific communication interventions may be designed to influence only one or several types of psychological processes. All sorts of psychological processes are expected to affect behavior even if communication is designed to influence only one of them. Communication affects behavior indirectly by providing information that changes one or all of such processes. Exogenous determinants including demographic, socioeconomic and contextual characteristics affect endogenous variables such as recall of communication messages, ideation and behavior.