Long-term follow-up study of IgM associated nephrotic syndrome patients: clinical outcome and prognostic indicators.

RATIONALE

Even though it is the most common primary glomerular disease, the natural history and prognosis of IgM associated nephrotic syndrome have not been well established.

OBJECTIVES

To determine the (1) responsiveness to prednisolone therapy, (2) long-term clinical and laboratory outcomes, and (3) prognostic indicators to prednisolone therapy in patients with IgM associated nephrotic syndrome.

STUDY DESIGN

Clinical descriptive, longitudinal study.

SUBJECTS

Seventy two biopsy-proved IgM associated nephrotic syndrome patients, diagnosed between 1978-1996 at Vajira Hospital, Bangkok, were included in the study.

METHOD

Clinical parameters with age, sex, duration of edema, blood pressure and laboratory findings such as hematuria, BUN, creatinine, albumin, and cholesterol, 24-hour urine protein, and stool examination, were collected pre-renal biopsy. Each patient was treated with 45-60 mg of prednisolone according to body weight, for up to 8 weeks. Each patient was followed-up every 4-weeks for clinical and laboratory evaluations, and for adjusting the steroid dosage. Clinical responses were stratified into 3 groups as steroid responsive (SRP), steroid dependent (SD), and steroid resistant (SRS).

MAIN OUTCOME MEASURES

(1) Frequency and types of steroid responsiveness. (2) Incidence of hypertension, hematuria, renal insufficiency, end-stage renal disease, and survival during the follow-up. (3) Prognostic indicators for initial clinical response to prednisolone, and for long-term morbidity and mortality.

RESULTS

Forty eight of the 72 patients (66.67%) were responsive to prednisolone at 8-weeks, the 24 remaining patients (33.33%) were nonresponsive. High proteinuria of 7.66 +/- 4.14 g/D was the only good prognostic indicator to initial prednisolone therapy (p < 0.03). During the follow-up, 42(58.33%), 26(36.11%), and 4(5.56%) patients were SRP, SD, and SRS, respectively. There were no prognostic indicators associated with long-term steroid responsiveness. Of the 60 patients followed-up for more than one year; 34, 15 and 11 patients were followed-up for 1-5, > 5-10 and > 10 years, respectively. Hematuria and proteinuria were more frequent among the SRS group (p < 0.01 and 0.02, respectively) during the follow-up. Only one patient, initially in the SD group, and later on became SRS, died.

CONCLUSION

Patients with IgM associated nephrotic syndrome had very good response to prednisolone therapy. It had a very slow progressive course, with low morbidity and mortality.