Notification of tuberculosis: how many cases are never reported?

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Medical Record Analysis

Background:

• Accurate tuberculosis (TB) notification is crucial for public health surveillance, including contact tracing and national incidence assessment.
• The reliability of current TB notification figures is questionable.
• This study investigates TB notification rates in East London.

Purpose of the Study:

• To examine the notification rates of tuberculosis (TB) in adult patients diagnosed at two London hospitals over a five-year period.
• To identify factors influencing the under-notification of TB cases.
• To assess the impact of under-notification on public health risk.

Main Methods:

• A retrospective survey of adult tuberculosis (TB) patients (aged 16+) was conducted at the London Chest Hospital and Royal London Hospital (1985-1989).
• Cases were identified using multiple data sources: microbiology, histology, statutory notifications, necropsy reports, coroners' records, hospital data, and death certificates.
• Notification status was cross-referenced with local authority records, and clinical data were extracted from case notes.

Main Results:

• Out of 609 identified adult TB cases, 580 (95%) had available records, with 426 (73%) successfully notified.
• Notification rates varied by clinical specialty; patients with prior TB history or those who died within a year were less likely to be notified.
• 14% of smear-positive TB cases (25/185) and 24% of smear-positive pulmonary TB cases (20/85) were not notified.

Conclusions:

• A significant proportion (27%) of tuberculosis (TB) cases were not notified in the study area.
• The under-notification of smear-positive TB cases represents a substantial public health risk due to potential transmission.
• The true incidence of TB in the studied area is likely at least one-third higher than official notification figures indicate.