Diagnostic completeness: the missing link in antimicrobial stewardship in low- and middle-income countries.

Antimicrobial resistance (AMR) is accelerating in low- and middle-income countries, yet antibiotic prescribing decisions are often made without diagnostic certainty. Diagnostic completeness - the systematic commitment to obtaining a confirmed diagnosis before initiating treatment - is an overlooked upstream component of antimicrobial stewardship. Without this pre-treatment commitment, downstream antimicrobial management efforts risk being bypassed because diagnostic testing is never ordered. Here, we distinguish diagnostic completeness from diagnostic stewardship: the former concerns whether a diagnosis is pursued before treatment, whereas the latter concerns whether the appropriate diagnostic test is used. Behavioural alerts, hub-and-spoke diagnostics, and incentive redesign are three practical pathways that could strengthen diagnostic completeness in primary care, although each faces well-documented implementation barriers requiring context-specific adaptation. We also address patient-level constraints, equity implications, health system heterogeneity, and empirical therapy in emergency contexts. Diagnostic completeness is a necessity; closing the diagnostic gap will not solve AMR alone, yet without it, stewardship will not suffice.