Frequency of extractable nuclear antigen seropositivity among individuals seronegative for antinuclear antibodies on indirect immunofluorescence: a systematic review and meta-analysis.
The frequency of extractable nuclear antigen (ENA) seropositivity in patients with negative antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) remains insufficiently characterized. We aimed to estimate the frequency of ENA seropositivity among ANA-IIF-negative ind…