A prediction risk score for HIV among adolescent girls and young women in South Africa: identifying those in need of HIV pre-exposure prophylaxis

Abstract

Background

In sub-Saharan Africa (SSA), adolescent girls and young women (AGYW) have the highest risk of acquiring HIV. This has led to several studies aimed at identifying risk factors for HIV in AGYM. However, a combination of the purported risk variables in a multivariate risk model could be more useful in determining HIV risk in AGYW than one at a time. The purpose of this study was to develop and validate an HIV risk prediction model for AGYW.

Methods

We analyzed HIV-related HERStory survey data on 4,399 AGYW from South Africa. We identified 16 purported risk variables from the data set. The HIV acquisition risk scores were computed by combining coefficients of a multivariate logistic regression model of HIV positivity. The performance of the final model at discriminating between HIV positive and HIV negative was assessed using the area under the receiver-operating characteristic curve (AUROC). The optimal cut-point of the prediction model was determined using the Youden index. We also used other measures of discriminative abilities such as predictive values, sensitivity, and specificity.

Results

The estimated HIV prevalence was 12.4% (11.7% − 14.0) %. The score of the derived risk prediction model had a mean and standard deviation of 2.36 and 0.64 respectively and ranged from 0.37 to 4.59. The prediction model’s sensitivity was 16. 7% and a specificity of 98.5%. The model’s positive predictive value was 68.2% and a negative predictive value of 85.8%. The prediction model’s optimal cut-point was 2.43 with sensitivity of 71% and specificity of 60%. Our model performed well at predicting HIV positivity with training AUC of 0.78 and a testing AUC of 0.76.

Conclusion

A combination of the identified risk factors provided good discrimination and calibration at predicting HIV positivity in AGYW. This model could provide a simple and low-cost strategy for screening AGYW in primary healthcare clinics and community-based settings. In this way, health service providers could easily identify and link AGYW to HIV PrEP services.

Keywords:

• HIV
• risk score
• adolescent girls and young women & pre-exposure prophylaxis

Acknowledgements

We would like to acknowledge South African Medical Research Council (SAMRC) for authorizing HERStory data to be used in the development of this risk prediction model.

Authors contributions

Study design: Moyo R, Govindasamy D, Nyasulu PS and Manda S; Data collection and cleaning: Govindasamy D; Data analysis and interpretation: Moyo R, Manda S, Nyasulu PS and Govindasamy D; Writing of the draft manuscript: Moyo R; Read and approve the final manuscript: All authors.

Availability of data and materials

The datasets analyzed during the current study are not publicly available due

Data protection policy of South African Medical Research Council (SAMRC) which only makes the data available on request. Data can be requested from SAMRC through Dr Darshini Govindasamy on [email protected]

Competing interests

The authors declare no competing interests.

Consent for publication

Not Applicable.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethics approval

This study was approved by Stellenbosch University health research ethics committee (S21/09/171). There was actual involvement of humans during data collection in the initial HERStory survey. All methods and procedures during data collection were conducted in accordance with relevant guidelines and regulations of research involving humans. Informed consent was obtained from all subjects and or participants representatives.

Additional information

Funding

This study was not funded.