CM-01. Glomerular filtration rate and the chronic lymphocytic leukemia patients survival

Summary

The glomerular filtration rate (GFR), a parameter reflecting the kidney function. Its decrease correlates with worse long-term prognosis and is more commonly seen in elderly patients. Chronic lymphocytic leukemia (CLL) is one of the most common lymphoproliferative conditions in the elderly (60-75 years) and senile (more than 75 years old) age patients. The aim of the study was identifying the relationship between GFR level and CLL patients survival.

Materials and methods

We analyzed the data of 123 patients (60 men and 63 women) diagnosed with CLL A-C according to Binet. In all patients the data on overall survival was available. Patients with HIV infection, as well as those with other cancers, were excluded from the study. At the time of CLL diagnosis the GFR was calculated using MDRD formula. For statistical evaluation of the obtained data, the average indicator value and its standard deviation value were calculated. Student’s t-test was used to compare the groups. The correlation analysis was carried out according to Pearson. The difference was considered statistically significant if p <0.05. The methods of data mining (IAD) were also used in the work. The main purpose of the IAD is searching for hidden patterns in the data checking hypotheses put forward by the researcher. The studied patients were divided into two classes: K1 (actual survival is less than the predicted median survival in accordance with the Binet stage) and K2 (actual survival is greater or equal to the predicted median survival in accordance with the Binet stage). The significance of GFR for patient survival was analyzed in these groups.

Results

The average age of men and women at the diagnosis of CLL was comparable and was 66.4±7.9 years and 67.7±9.6 years, respectively (p≥0.05). The GFR value for MDRD showed significant gender differences. This parameter was significantly lower in women – 58.7±12.4 ml/min/1.73 m² compared to the group of men – 68.8±9.1 ml/min/1.73 m² (p<0.05). Interesting results were obtained in the group of men studied by the IAD method. If the GFR MDRD value is more than 76.5 ml/min/1.73 m², then we can say that the patient will overcome calculated parameters of the median survival for corresponding CLL Binet stage. Otherwise, the overall survival of the patient will be less than estimated median survival according to Binet. This finding was patented (Patent RU 2725877 C1). It should be noted that no similar results were obtained in the group of female patients. Perhaps this is due to the presence of more subtle influences that still need to be established. Nevertheless, when comparing the parameters of GFR at the time of CLL diagnosis and the data on overall survival, a direct correlation of an average degree was revealed (r=0.58, p=0.02). It is known that a decrease in the GFR is associated with most significant deterioration of the long-term prognosis, and it is increasingly common in the general population among the elderly [Coresh J. et al., 2003; Li S. et al, 2005]. In addition to age, the paraneoplastic process itself also negatively affects the kidney function. A number of mediators produced by the tumor tissue itself or by immunocompetent cells in response to its growth cause the formation of paraneoplastic glomerulonephritis [Ohtani H. et al, 2004]. In this case, the actual tumor cells in the renal tissue, as a rule, are not found. As a result, the so-called membranous nephropathy is formed. This is one of the most common variants of paraneoplastic kidney damage [Preston R. A. et al. 1990].

Conclusion

In general, the study showed the need to take into account the value of GFR in patients with CLL, since a clear relationship between this parameter and the overall survival of patients was revealed. It is possible that the optimization of GFR can improve the prognosis of such patients, but the latter requires further study.

Keywords

Chronic lymphatic leukemia, overall survival, glomerular filtration rate, data mining.