This study found that a little more than half of the FSWs in Karnataka, India have engaged in risky sexual practices, measured using a summary measure of HIV risk and vulnerability. In addition, FSWs from Belgaum are more likely to engage in risky sexual practices than those from Bangalore. This may be the reason why HIV prevalence among FSWs in Belgaum is two times higher than among Bangalore-based FSWs 
. Multivariate analysis indicated that engaging in risky sexual practices is positively associated with being older, currently married, in sex work for a longer duration, and having three or more clients a day. Post-hoc analysis suggests these groups of FSWs comprise 80% of the study population. Previous research studies conducted in India have also identified these factors as being associated with higher HIV infection among FSWs 
. The current study also notes that certain characteristics of FSWs are positively associated with one behavior, but negatively associated or not associated statistically with another behavior. For example, inconsistent condom use is higher among middle aged FSWs, concurrency is higher among those in the younger group, consumption of alcohol prior to sex is higher among older sex workers and finally, the practice of anal sex has no association with age of the sex worker. In this context, the summary measure of risky sexual practices could identify the most-at-risk group of FSWs, which can help program implementers to develop more definitive outreach strategies. Moreover, targeting these FSWs can help the program address both their vulnerabilities and risk behaviors simultaneously.
The study findings also suggest that more than two-thirds of FSWs have engaged in unprotected sex with their sexual partners. Evidence from research in India suggests that consistent condom use is considerably high with commercial partners 
, but has remained low with non-commercial partners 
. The low level of condom use in non-commercial relationships can be due to the intimacy and trust involved in such relationships 
; condom use in such relationships is most often perceived as a symbol of infidelity and fosters mistrust 
. Further, the considerable proportion of FSWs involved in concurrent relationships coupled with high inconsistent condom use can lead to the transmission of STI/HIV infection at a much faster rate. Therefore, HIV prevention programs need to create greater awareness about the risk associated with non-use of condoms in non-commercial relationships with more emphasis on FSWs who have concurrent relationships. FSWs who are 25 years or older, currently married, and those entertain three or more clients a day should be given more attention than other sex workers to improve their condom use practices.
This study documented that 12% of FSWs had engaged in anal sex in Karnataka, which is considerably lower than findings from other research conducted in India among sex workers 
. In these studies, around one in four FSWs reported ever engaging in anal sex with their sexual partners. The current study findings suggest that FSWs who have been in sex work for 10 years or more and have three or more clients a day are more likely to engage in anal sex than their counterparts. Similar findings are noted in another study conducted in East Africa 
. Post-hoc analysis suggests that 62% of FSWs who have been in sex work for 10 years or more are 35 years or older. Evidence suggests that older sex workers get fewer clients to entertain than younger sex workers, 
which may create a sense of fear among these FSWs regarding their survival in light of the reducing number of clients. Therefore, these FSWs succumb to the demands made by their clients which could be related to the type of sex, particularly anal sex, the place of sex or alcohol consumption 
This study found that more than half of the sex workers consumed alcohol prior to sex, which is similar to findings from another Indian study 
. Empirical research has opined that alcohol use depends on the type of client with whom FSW have sex. FSWs consumed alcohol to enhance their enjoyment and involvement while having sex with regular clients, whereas with one-time clients, they consumed alcohol to become insensitive to take clients without emotional involvement 
. The study findings also indicate that brothel-based FSWs and those getting clients through brokers/pimps were more likely to report alcohol consumption prior to sex than their counterparts. This could be due to the fact that alcohol is available within brothels and in nearby areas, and clients bring alcohol with them when they visit sex workers in these settings 
. As these clients are accessible to sex workers only through a pimp or broker, structural interventions to increase awareness about the harm associated with alcohol use can be designed targeted at these stakeholders in sex work.
This study noted that a significantly higher proportion of sex workers in Belgaum than in Bangalore engage in risky sexual practices. In fact, the difference between these districts is more prominent in the practice of anal sex and alcohol consumption prior to sex than that in inconsistent condom use and concurrent sexual relationships. This difference could be due to the socio-cultural practices related to sex work practices in these districts. In Belgaum, the practice of sex work is concentrated in semi-urban and rural areas, characterized by the presence of traditional sex worker (Devadasi) and solicitation occurs primarily in non-street-based settings (home and brothel) 
; however, in Bangalore sex work is concentrated in urban areas and most FSWs solicit clients in street-based venues. Mapping data from these districts suggest that the number of sex workers in Belgaum is much less than in Bangalore 
. Further, FSWs in Belgaum are highly mobile, visiting districts in the nearby state of Maharashtra 
. These factors either directly or indirectly affect the HIV risk behavior of FSWs as well as their clients. Therefore, these differences and contextual factors need to be taken into account while implementing HIV prevention programs in these districts.
Though the study findings are of utmost importance for HIV prevention programs and research, these findings must be interpreted in light of the following study limitations. First, the survey did not collect any biological information and hence, one cannot ascertain if the risk groups identified here also have higher STI/HIV infection rates. However, contemporary research studies that collected biological specimens suggest similarities in the risk group identified 
. Second, previous research suggests that the prevalence of anal sex may have been under-reported, as the information was self-reported and the stigma associated with reporting such sensitive experiences is well recognized in many research studies 
. Third, to measure concurrency, this study used the partner calendar method to gather information on duration of relationships with different sexual partners. Though this method provides more data, there may be recall bias/errors related particularly to the start and end dates of partnerships. However, previous research suggests that the estimates provided by this method of data collection can be considered reliable 
. Fourth, data were collected in a cross-sectional survey and hence, the cause–effect relationship is difficult to establish. Fifth, there could be some extent of bias due to the use of the cluster sampling method to select hotspots. Despite these limitations in this study, the evidence from this study can guide policy makers in devising strategies for optimum outreach and service provision. Special prevention strategies need to be designed to increase risk perception about HIV among the most-at risk group of FSWs identified in this study.
In summary, this study identified four most-at risk groups of sex workers: 35 years or older, currently married, engaged in sex work for 10 years or more and have sex with three or more clients a day. HIV prevention programs should be able to cover more than 80% of FSWs if they target these sub-groups of sex workers. Special attention is needed in such programs at clinics to build the skills of FSWs on safe sex negotiation with clients. Further, the most-at-risk groups of sex workers identified are in disadvantaged life situations. Hence, efforts should be made to increase their earning from sources other than sex work through alternate livelihood mechanisms. Collectivization of FSWs is another important aspect that can bring these sex workers together in one place where they can be educated about safe sex practices. These initiatives also need to undertake awareness campaigns within sex work settings to educate both clients and FSWs on the need for safe sex practices. Advocacy with community stakeholders as well as with brothel owners and pimps can be another approach to reach these sex workers. Vulnerability to HIV risk through alcohol consumption can be reduced through risk reduction counseling and harm reduction measures. In addition, developing district specific intervention strategies that consider the prevailing socio-cultural norms in the district may yield better outcomes in HIV prevention programs.