Selective Screening for Complement DEficiencies in Patients with Meningocaccal Disease

To The Editors: We write in response to the recent letter by Leggiadro, 1 which stressed the importance of diagnosing complement deficiencies (CD) in patients with meningococcal disease (MCD). This is in contrast to our service where following a review of 297 MCD patients, we do not routinely screen for CD (incidence, 0.3%). 2 In the US MCD is rare (1.1/100 000; <1 year, 10.7/100 000; 1 to 4 years, 4.7/100 000 3) compared with England, Wales and Northern Ireland (9.1/100,000; <1 year, 162/100 000; 1 to 4 years, 50.9/100 000 4, 5). Incidences vary considerably in other countries. 6–8 Epidemiologic data, first documented by Densen, 9 showed that as the incidence of MCD increases the incidence of CD decreases. The prevalence of CD in patients with MCD varies from <1% to 50%. 9 It is postulated that in epidemic areas protective antibodies rates are low and therefore complement sufficient patients are more likely to be infected than those with CD. The converse is true in regions where is MCD rarer, i.e. the US. In regions where MCD is relatively common, we suggest CD should be investigated in the following situations: where MCD has been attributed to an unusual serogroup (i.e . not B or C); in patients who have had two separate proven episodes of MCD; and in meningococcal serogroup C vaccine failures. The last category, difficult to define, comprises patients with MCD who have had significant and or recurrent bacterial infection previously. 2 When considering whether to screen MCD patients for CD the local incidences of MCD and if available of CD (in MCD patients) should guide judgments. In regions where universal screening is not adopted, we suggest that patients fulfilling any of the above criteria should be screened. Scott J. Hackett, M.B., Ch.B., M.R.C.P. (UK) Terence J. Flood, M.A., M.R.C.P.I.