title: The International Scoring System (ISS) for multiple myeloma remains a robust prognostic tool independently of patients' renal function.
abstract: BACKGROUND
  The International Staging System (ISS) is the most widely used staging system for patients with multiple myeloma (MM). However, serum β2-microglobulin increases in renal impairment (RI) and there have been concerns that ISS-3 stage may include 'up-staged' MM patients in whom elevated β2-microglobulin reflects the degree of renal dysfunction rather than tumor load.
  
  
  METHODS
  In order to assess the impact of RI on the prognostic value of ISS, we analyzed 1516 patients with symptomatic MM and the degree of RI was classified according to the Kidney Disease Outcomes Quality Initiative-Chronic Kidney Disease (CKD) criteria.
  
  
  RESULTS
  Forty-eight percent patients had stages 3-5 CKD while 29% of patients had ISS-1, 38% had ISS-2 and 33% ISS-3. The frequency and severity of RI were more common in ISS-3 patients. RI was associated with inferior survival in univariate but not in multivariate analysis. When analyzed separately, ISS-1 and ISS-2 patients with RI had inferior survival in univariate but not in multivariate analysis. In ISS-3 MM patients, RI had no prognostic impact either in univariate or multivariate analysis. Results were similar, when we analyzed only patients with Bence-Jones >200 mg/day.
  
  
  CONCLUSIONS
  ISS remains unaffected by the degree of RI, even in patients with ISS-3, which includes most patients with renal dysfunction.
authors.affiliation: Department of Clinical Therapeutics, University of Athens School of Medicine, Athens. Electronic address: mdimop@med.uoa.gr.
authors.forename: M A
authors.initials: MA
authors.lastname: Dimopoulos
authors.affiliation: Department of Clinical Therapeutics, University of Athens School of Medicine, Athens.
authors.forename: E
authors.initials: E
authors.lastname: Kastritis
authors.affiliation: Department of Hematology, 'G. Gennimatas' Hospital, Athens.
authors.forename: E
authors.initials: E
authors.lastname: Michalis
authors.affiliation: Department of Haematology, Democritus University of Thrace Medical School, Alexandroupolis, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Tsatalas
authors.affiliation: Department of Haematology, Nicosia General Hospital, Nicosia, Cyprus.
authors.forename: M
authors.initials: M
authors.lastname: Michael
authors.affiliation: Department of Hematology, 'Saint Savvas' Anticancer Hospital, Athens.
authors.forename: A
authors.initials: A
authors.lastname: Pouli
authors.affiliation: Department of Hematology, Chalkis General Hospital, Chalkis.
authors.forename: Z
authors.initials: Z
authors.lastname: Kartasis
authors.affiliation: Department of Hematology, 'Evangelismos' Hospital, Athens.
authors.forename: S
authors.initials: S
authors.lastname: Delimpasi
authors.affiliation: Department of Clinical Therapeutics, University of Athens School of Medicine, Athens.
authors.forename: D
authors.initials: D
authors.lastname: Gika
authors.affiliation: Fourth Department of Internal Medicine, 'Attikon' University Hospital, Athens.
authors.forename: A
authors.initials: A
authors.lastname: Zomas
authors.affiliation: Department of Clinical Therapeutics, University of Athens School of Medicine, Athens.
authors.forename: M
authors.initials: M
authors.lastname: Roussou
authors.affiliation: First Department of Medicine, University of Athens School of Medicine, Athens.
authors.forename: K
authors.initials: K
authors.lastname: Konstantopoulos
authors.affiliation: Third Department of Internal Medicine, Red Cross Hospital 'Korgialenio Benakio', Athens.
authors.forename: A
authors.initials: A
authors.lastname: Parcharidou
authors.affiliation: Department of Hematology, 'Theagenion' Cancer Center, Thessaloniki, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Zervas
authors.affiliation: Department of Clinical Therapeutics, University of Athens School of Medicine, Athens.
authors.forename: E
authors.initials: E
authors.lastname: Terpos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood* / Q000150:complications / Q000473:pathology*; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D051437:Renal Insufficiency / Q000097:blood / Q000150:complications; D055815:Young Adult; D001613:beta 2-Microglobulin / Q000097:blood*
chemical_list: D001613:beta 2-Microglobulin