Effect of Splenectomy on Risk of Infection and other Complications among Sickle Cell Disease patients in Al-Ahsa Area -A retrospective cohort study

Sickle cell anemia is one of the common inherited hemoglobinopathies in the Kingdom of Saudi Arabia, with the highest frequency in the Eastern province, of which Al-Ahsa region is a constituent part. A number of sickle cell disease (SCD) patients undergo surgical splenectomy to minimize the side effects of hypersplenism. The objectives of this study were to determine the effect of surgical splenectomy on the occurrence of infections and vasoocclusive/ painful crisis in SCD patients in Al-Ahsa area, and to study its effect on the need for blood transfusion and admission into hospital. The study was conducted as a retrospective cohort study among SCD patients registered in Al-Ahsa area hospitals at end of 1424 H, with an outcome assessment period of one year (1425 H). The study population included all SCD patients who were resident of Al-Ahsa area and registered at any of the secondary/tertiary care hospitals of the city including King Fahad Hospital, Hofuf; Prince Saud Bin Jalawey Hospital; or in Pediatrics Hospital, Hofuf on 30/12/1424 H (20/2/2004 G).

The study population was divided into two groups: exposure and comparison cohort. Exposure Cohort included any member of study population who had surgical splenectomy by 30-12-1424 H (20-2-2004 G). Comparison Cohort included any member of study population who did not have surgical splenectomy by 3012-1424 H (20-2-2004 G). Any patient below 6 months of age on that date were excluded. Study subjects were selected by simple random technique out of the eligible study cohorts, without matching. With a ratio of unexposed group to exposed of 3:1. A structured questionnaire was designed, and data collection extended for about two months from 11/01/1426 to 07/03/1426 H.

A total of 113 SCD patients who had splenectomy were recruited as exposed group. Their ages ranged from 5 to 52 years (mean 18.34, SD 9.55). Males constituted 62.8%, and all were Saudis. Based on hemoglobin electrophoresis, 47.9% of splenectomized cases had HbS ranging from 50 to 70%, 47.9% had HbS from 71 to 90% and only 4.2 % had HbS above 90% at time of initial diagnosis. In addition to SCD, 33.6% had other hematological diseases; 1.8% had alpha thalassemia, 6.2% Beta-thalassemia major, 9.7% Beta-thalassemia minor, 18.6% G6PD deficiency and 0.9% had Henoch Schonlein Purpura (HSP), 3.5% had both Betathalassemia minor and G6PD deficiency. Ages at time of splenectomy varied from 2 to 49 years (mean 14.4, SD 9.17), the largest proportion (42.3%) was splenectomized by 10 years of age.

A total of 311 SCD patients without splenectomy were recruited as comparison group. Their ages ranged from 2-48 years (mean 14.9, SD 9.5). Males constituted 60.5%. Based on hemoglobin electrophoresis, 52.5% of had HbS ranging from 50-70%, 46.1% had HbS from 71-90%, and only 1.4% had HbS above 90%; at time of initial diagnosis; with no significant difference between the splenectomized and the non-splenectomized cases (P= 0.239). In addition to SCD, 28% had other hematological disease. Splenectomized patients were vaccinated significantly more than those non-splenectomized (P< 0.001). Splenectomized patients had received statistically significantly more Pneumococcal and Hib vaccine. Among the non-splenectomized patients only 0.6% used benzathine penicillin regularly, and 2.6% used Ospen (phenoxymethylpenicillin) regularly, which was statistically significantly lower than the splenectomized patients (P< 0.001).

Among the splenectomized patients, 47.8% had at least one hematological or infectious event during the period of follow-up, as compared to 88.7% among non-splenectomized cases (Table 1). The mean of hematological or infectious events among splenectomized patients was 2.82 during the period of follow-up as compared to 5.35 events among nonsplenectomized patients (P< 0.001).

Considering only infectious events, 7.1% had at least one infectious event during the period of follow-up as compared to 21.5% among nonsplenectomized cases (Table 1). The mean of any infectious event among splenectomized patients was 0.089 as compared to 0.25 among non-splenectomized patients (P = 0.002).

Considering for hematological events only, 47.8% of splenectomized cases as compared to 88.7% of nonsplenectomized cases had at least one hematological event (Table 1). The mean of any hematological event among splenectomized patients was 2.73 as compared to 5.10 among non-splenectomized patients (P<0.001).

When both groups were compared for health care needs, it was observed that 3.5% of splenectomized cases as compared to 37.3% of nonsplenectomized cases had received at least one blood transfusion (Table 1). Mean number of transfusions among splenectomized patients was 0.12 as compared to 0.60 among nonsplenectomized patients (P<0.001). Regarding hospital admission during the follow-up period, 43.4% of splenectomized cases as compared to 87.8% had at least one admission to the hospitals (Table 1). The mean episodes of admission into hospital among splenectomized patients was 1.23 as compared to 2.45 among nonsplenectomized patients (P <0.001).

SCD is a relatively common genetic disorder in the Eastern region of the Kingdom and, with the associated complications, whether hematologic or infectious, poses a heavy burden on patients, their families and health care system.[1-4] As observed in this study, non-splenectomized SCD patients suffered on average over 5 of such episodes in one year, leading to a mean admission rate of 2.45 times in the same period. The main constituent of the problem was a variety of hematological crisis in the form of vasoocclusive crisis, painful crisis and bone crisis.

As part of the comprehensive management protocol of SCD patients, splenectomy has been practiced as a popular surgical procedure in patients with hypersplenism, to reduce hematological complications. The few studies conducted to evaluate the impact of this procedure showed that risks of hematological crisis (aplastic, hemolytic, acute sequestration, vasoocclusive/painful) in splenectomized patients were significantly low as compared to non-splenectomized patients.[5,6] This study also demonstrated that splenectomy has been a successful procedure in this regard and has been able to decrease the incidence of hematological events almost by half. Advantages of this reduction in complication was also evident in the hospital admission, which was also halved among splenectomized patients; whereas the number of blood transfusions were almost one fifth among splenectomized as compared to nonsplenectomized patients, during one year of study. Although the study did not attempt to perform the cost benefit analysis of this procedure, but expectantly the cost of procedure is outweighed by the decrease in the cost of health care in the longer run; while the long term reduction in the patient suffering is quite obvious. So on the basis of this study we can safely recommend

that splenectomy should be encouraged among sickle cell disease patients with recurrent attacks of vasoocclusive crises, repeated admissions, and frequent blood transfusions.