Objective: The haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) are rare disorders characterised by intravascular platelet aggregation and widespread thrombus formation in the microcirculation resulting in tissue ischaemia. A retrospective analysis was carried out in 136 patients with HUS or TTP hospitalized from April 1991 through March 2004 in three tertiary referral hospitals of Shiraz (the largest city in southern Iran) to evaluate the epidemiological aspects, clinical characteristics and laboratory findings of the two diseases.
Methods: One hundred and one cases of HUS (49 females and 52 males) and 35 cases of TTP (21 females and 14 males) were identified. The mean age was 3.5 years for HUS, 30.8 years for TTP.
Results: The mean annual incidence rate of HUS decreased approximately 30-fold throughout the observed period, while the incidence rate of TTP increased approximately 6-fold. A seasonal pattern was noted for both TTP and HUS, with the highest incidence during the summer months. Twenty patients with HUS and 16 patients with TTP died, resulting in case fatality rates of 19.8% and 45.7%, respectively. No prognostic factor was identified for TTP, whereas signs of neurological impairment and high leucocyte counts had an adverse effect on the prognosis of HUS patients.
Conclusions: This study shows that, in contrast to other countries, the incidence rate of HUS shows a decreasing trend in southern Iran, probably related to the prevention of gastrointestinal diarrhoeal infections (especially Escherichia coli 0157:H7) and to their improved management. The incidence of TTP is increasing in Iran as in other countries.