NxStage Announces Access to Demographic and Outcomes Information for the Growing U.S. Daily Home Hemodialysis Patient Population

Wednesday July 23, 2008

LAWRENCE, Mass., July 23 /PRNewswire-FirstCall/ — NxStage Medical, Inc. (Nasdaq: NXTM), a leading manufacturer of innovative dialysis products, today announced ongoing public access to current summary information derived from a registry of NxStage patients with end-stage renal-disease (ESRD) who undergo hemodialysis at home on a more frequent, or daily, basis as an alternative to the conventional regimen of therapy received three times a week at a dialysis center.

This unique, quantitative portrait of key characteristics of ESRD patients who have been receiving daily home hemodialysis, which includes correlation with survival and kidney transplant relative to that observed with conventional hemodialysis, reflects more than a thousand patient years of experience and more than one million treatments. This is believed to be the largest known database of home hemodialysis patients.

Key statistics from the registry, which are available on the NxStage web site (http://www.nxstage.com/chronic_renal_care/registry/), include the following:

— Survival and transplant rates are notably higher among the NxStage patient population undergoing daily therapy vs. reported figures for conventional, less frequent dialysis treatment. NxStage patients on home daily hemodialysis experienced a better than 50% reduction in expected mortality compared to the overall U.S. hemodialysis patient population. This observed difference was statistically significant (P<0.0001).

— Patients of varied size, age, vascular access type, and geographic location are participating in home daily hemodialysis, indicating its broad applicability.

— 92% of the U.S. dialysis population resides within 60 miles of a center offering NxStage home hemodialysis training, and nearly 80% are within 30 miles. This indicates that geographic barriers to initiating daily home hemodialysis are being addressed.

In compiling the survival and kidney transplant analysis, NxStage captured mortality data from 2,553 patients using the NxStage System One, from over 300 dialysis centers, totaling 1,603 patient years of experience. This data was then compared to mortality rates reported in the United States Renal Data System for 2007 using a Standard Mortality Ratio (SMR) methodology, adjusting for patient age and gender.

According to Dr. Alan Hull, Chief Medical Advisor of NxStage Medical, With its unique leadership position in the growing home daily hemodialysis movement, NxStage has a commitment to share data and insight gleaned from continuing use of this therapy with patients, physicians and providers. The information that NxStage is making available, while not derived from a controlled study, provides a current, accurate picture of who is participating in daily home hemodialysis and a longitudinal view of the clinical outcome trends emerging from the growing use of this therapy. We will continue to enhance collective knowledge about the use of daily home hemodialysis via ongoing access to our database, which will be updated on at least a semi-annual basis, as well as our concurrent efforts to definitively establish long term outcomes via initiatives such as our FREEDOM Study.

The growth of NxStage therapy in the three years since its FDA clearance for home use has led to a more than doubling of the number of patients experiencing the potential benefits of home hemodialysis.

NxStage was founded on our belief in the clinical benefits of daily home hemodialysis for patients with ESRD, said Jeffrey H. Burbank, President and Chief Executive Officer of NxStage Medical. It is gratifying to see these benefits experienced by our own patients. We are dedicated to improving patient access to this important therapy, and hope that sharing this current data with the kidney care community will help build awareness of daily home hemodialysis, and provide patients and caregivers alike with information that helps them make informed decisions about their care, said Mr. Burbank.

About NxStage Medical

NxStage Medical, Inc. (Nasdaq: NXTM) is a medical device company, headquartered in Lawrence, Massachusetts, USA, that develops, manufactures and markets innovative products for the treatment of end-stage renal disease, or ESRD, and acute kidney failure. For more information on NxStage and its products, please visit the Company’s website at http://www.nxstage.com.

Forward-Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this release that are not clearly historical in nature are forward-looking, and the words anticipate, believe, expect, estimate, plan, and similar expressions are generally intended to identify forward-looking statements. Examples of these forward-looking statements include statements as to the benefits of daily home hemodialysis, expectations relating to our ability to build upon positive clinical data relating to home daily hemodialysis, expectations regarding our ability to update the data referenced on a semi-annual basis, and expectations relating to improving patient and physician awareness, and access to, home daily hemodialysis. All forward-looking statements involve risks, uncertainties and contingencies, many of which are beyond NxStage’s control, which may cause actual results, performance, or achievements to differ materially from anticipated results, performance or achievements. Certain factors which may affect future operating results are detailed in NxStage’s filings with the Securities and Exchange Commission, including the Annual Report on Form 10-Q for the three months ended March 31, 2008. In addition, the statements in this press release represent NxStage’s expectations and beliefs as of the date of this press release. NxStage anticipates that subsequent events and developments may cause these expectations and beliefs to change. However, while NxStage may elect to update these forward-looking statements at some point in the future, it specifically disclaims any obligation to do so, whether as a result of new information, future events, or otherwise. These forward-looking statements should not be relied upon as representing NxStage’s expectations or beliefs as of any date subsequent to the date of this press release.

Important Additional Information

A special meeting of NxStage stockholders will be held on Thursday, July 31, 2008 to obtain stockholder approval for the second closing of a $43 million private placement in NxStage. In connection with the private placement and required stockholder approval, NxStage filed with the SEC a definitive proxy statement on July 8, 2008. This proxy statement was mailed to NxStage’s stockholders on or about July 9, 2008. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE PROXY STATEMENT AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT NXSTAGE AND THE PRIVATE PLACEMENT. Investors and security holders may obtain free copies of these documents and other documents filed with the SEC at the SEC’s website at www.sec.gov, at NxStage’s website at www.nxstage.com or by writing to NxStage Medical, Inc., 439 S. Union St., 5th Floor, Lawrence, Massachusetts 01843, Attention: Investor Relations.

NxStage, its directors and the affiliates of its directors may be deemed to be participants in the solicitation of proxies with respect to the private placement. A description of the interests in NxStage of its directors, officers and such affiliates is set forth in NxStage’s proxy statement for its 2008 annual meeting of stockholders, filed with the SEC on April 29, 2008, and is included in the definitive proxy statement relating to the private placement and required stockholder approval filed with the SEC on July 8, 2008. These documents are available free of charge as described above.

Investor Relations Contact
Kristen Sheppard
NxStage Medical, Inc.

Media Contact
Jane Hauser
Schwartz Communications, Inc.

SOURCE NxStage Medical, Inc.

Web site: http://www.nxstage.com