NxStage Medical Reports First Quarter 20...($31005 $8374 ...),Health

NxStage Medical, Inc.

Home Market Metrics

March 31, December 31, March 31,

2008 2007 2007

Home patients prescribed to receive

therapy 2481 2223 1295

Home dialysis centers with System One 355 334 200

Non-GAAP Financial Measures

The Company discloses certain non-GAAP financial measures to supplement the Company's consolidated financial statements presented on a GAAP basis. These non-GAAP measures are not in accordance with, or an alternative for, generally accepted accounting principles in the United States. Management believes presenting Adjusted EBITDA (EBITDA adjusted for stock based- compensation and deferred revenue recognized) allows investors greater transparency to one measure used by management to understand cash use at the Company. The non-GAAP financial measures are reconciled to the most comparable GAAP financial measure below.

NxStage Medical Inc.

Non-GAAP Financial Measures

Three Months Ended

(Amounts in millions) March 31,

2008 2007

Loss from operations $13.2 $12.7

Depreciation and amortization (4.2) (1.4)

Stock-based compensation (1.5) (0.8)

Deferred revenue recognized 0.8 0.2

Adjusted EBITDA loss $8.3 $10.7

Projections of Adjusted EBITDA loss for the three months ended June 30, 2008 and year ended Decemb
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