Decline in malaria test positivity rates following capacity building and archiving of malaria rapid diagnostic test cassettes in Oyo State, Nigeria: a retrospective review of records

Abstract

Background: The malaria test positivity rate (TPR) is a key indicator for evaluating the effectiveness of malaria interventions. In Nigeria, routine data from January to June 2021 reported consistently high TPRs, ranging from 73 to 82%, while Oyo State reported TPRs of 70% to 74% during the same period. These figures were inconsistent with malaria therapeutic efficacy studies conducted between October 2009 and November 2010, which reported a much lower TPR of 35%. This discrepancy raised concerns about data quality, increased malaria incidence, or inaccuracies in malaria diagnosis.

Methods: This study assessed the effect of two interventions aimed at improving the accuracy of TPR data using secondary quantitative data from the National District Health Information System (NDHIS) for both Primary Healthcare Facilities (PHFs) and Secondary Health Facilities (SHFs). The interventions included (1) facility-level audits of used malaria Rapid Diagnostic Test (RDT) cassettes archived at 733 PHFs, initiated in September 2021, and (2) a 10-day basic malaria microscopy training (BMMT) for Laboratory Scientists at 17 SHFs, completed in September 2021.

Results: At PHFs, the RDT positivity rate declined from 71% in October 2021 to 53% in December 2022. A period review from January to September revealed a decrease in TPR from 62 to 53% in 2022, compared to no difference in TPR for the same period in 2021 with an average TPR of 77%. A paired t-test comparing the mean TPR for each period showed a statistically significant decline of 19.56 (t = 18.081, p < 0.01, CI (17.06-22.05). At SHFs, microscopy-based TPR decreased from 40% in October 2021 to 18% in December 2022. A review of January to September 2021 showed a TPR decline from 53 to 50%, while in 2022, TPR decreased from 25 to 18%. A paired t-test revealed a statistically significant decline of 19.33 in mean TPR at SHFs (t = 8.14, p < 0.01, CI 13.86-24.81).

Conclusion: This study highlights the critical role of auditing used RDT cassettes and recommends scaling up this approach in PHFs. It also underscores the value of basic malaria microscopy training in improving the quality and accuracy of microscopy-based diagnosis. One limitation of this study is the absence of comparative data from other states in Nigeria where the interventions were not implemented.

Keywords: Audit; Cassette archiving; Diagnosis; Health facilities; Malaria RDT; Microscopy; Test positivity rate.

Fig. 1

Malaria RDT test positivity rate across primary health facilities from January 2021–December 2022

Fig. 2

Malaria microscopy test positivity rate across 17 selected secondary health facilities from January 2021 to December 2022