ADA levels by type of pleural effusion in three tuberculosis pleural effusion prevalence periods (1998–2000, prevalence: 31.3%; 2001–2004, prevalence: 11.8%; and 2005–2008, prevalence: 7.4%).

CTPE: confirmed pleural tuberculosis; PTPE: probable pleural tuberculosis; CPE: complicated parapneumonic effusion; UPE: uncomplicated parapneumonic effusion.