NxStage(R) Medical and Renal Advantage Collaborate to Increase Awareness and Availability of Home Hemodialysis Therapies

Thursday March 8, 2007

LAWRENCE, Mass. and BRENTWOOD, Tenn., March 8 /PRNewswire-FirstCall/ — NxStage Medical, Inc. (Nasdaq: NXTM), the manufacturer of the NxStage System One&#153 portable kidney dialysis machine, and Renal Advantage Inc., the fourth largest provider of dialysis services in the United States, today announced specific collaborations intended to expand access to home hemodialysis therapies. As part of an agreement signed in February 2007, the companies will work together to increase the availability of home hemodialysis therapy to patients who may benefit and will collaborate on therapy development in selected strategic markets that Renal Advantage serves. As part of the agreement, Renal Advantage has purchased the majority of NxStage’s System One equipment currently in use.

Renal Advantage announced that it seeks to participate across its facilities in NxStage’s FREEDOM study, a prospective observational clinical trial designed to provide insight into the clinical and economic impact of home daily hemodialysis therapy. Renal Advantage has two sites currently participating in the study, and the site qualification process is currently underway at additional facilities.

The companies also will recognize World Kidney Day, March 8, 2007, by jointly hosting patient education and awareness sessions at Renal Advantage facilities in Omaha, Nebraska, and Richmond, Virginia. Existing in-center dialysis patients and the local community are invited to learn more about daily home hemodialysis, Renal Advantage and the NxStage System. Clinicians from the center, current home hemodialysis patients and representatives from NxStage will be available to talk with kidney patients and their families about treatment options, including daily home hemodialysis.

We have developed a close relationship with Renal Advantage over the last 18 months, and we appreciate the confidence in our therapy and technology that this agreement represents, said Jeffrey H. Burbank, President and CEO of NxStage Medical. Renal Advantage has expressed a real passion for home hemodialysis, and we look forward to NxStage’s role in their future plans.

Renal Advantage is committed to making home and daily hemodialysis available to its patients and physicians because of the enhancement to quality of life and potential clinical advantages, stated Dean Weiland, COO of Renal Advantage. NxStage technology, in its simplicity and portability, makes the benefits of home hemodialysis available to more patients. We’re confident that more patients and physicians will become aware of this viable therapy through this collaboration.

The NxStage System One is the first truly portable hemodialysis system cleared for home use by the FDA. Unlike traditional dialysis equipment, the System One plugs into standard electrical outlets, requires no special infrastructure to operate and is easy to use by trained patients accompanied by their trained partners. Patients who use the NxStage System One have the personal freedom to conduct prescribed treatments at home on their own schedule and more frequently. An additional benefit of the System One is the ability to travel with it.

About End-Stage Renal Disease:

End-stage renal disease is the permanent failure of the kidneys to filter the body’s wastes. It is most commonly caused by diabetes, hypertension or genetic disorders. In order to survive, ESRD patients must use some form of therapy to replace the function of the kidneys for the rest of their lives. Currently, over 450,000 patients in the United States suffer from ESRD, and the costs of treating ESRD patients are more than $20 billion annually in the United States. Due to increases in diabetes, hypertension and the aging of the U.S. population, those figures are projected to double within the next 10- 15 years. The most common form of kidney replacement therapy in the United States today is hemodialysis, which is used by over 350,000 patients currently. The great majority of these patients are treated with conventional, in-center hemodialysis, requiring patients to travel to a nearby dialysis center to cleanse their blood three times per week, where they are connected to dialysis machines for treatments lasting approximately three to four hours.

About Hemodialysis:

Today, most patients undergo hemodialysis therapy three times a week in outpatient dialysis centers. This differs significantly from the 24/7 workings of the naturally functioning kidney. Increasingly, clinicians and patients have recognized opportunities for therapy improvements with more frequent, or daily, dialysis. More than a hundred clinical papers have reported on the health and quality of life benefits of hemodialysis done more frequently. The reported benefits include reduced hypertension, reduced cardiac strain and left ventricular hypertrophy, reduced amyloid disease, and improved anemia status, appetite, and quality of life, including the ability to return to work.

About NxStage Medical:

NxStage Medical, Inc. (Nasdaq: NXTM) is a medical device company, headquartered in Lawrence, Massachusetts, USA, that develops, manufactures and markets innovative dialysis systems 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 www.nxstage.com.

About Renal Advantage Inc.:

Based in Brentwood, Tennessee, Renal Advantage Inc. provides dialysis services to patients with chronic kidney failure, also known as end-stage renal disease (ESRD). Renal Advantage provides services to approximately 7,400 patients in 80 dialysis facilities in ten states. Founded by veteran healthcare executives, the Company’s growth plan began with its acquisition of 73 dialysis centers in October 2005, which was financed in partnership with Welsh, Carson, Anderson & Stowe. For more information, visit the Company’s website at www.renaladvantage.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 anticipated demand for home and or daily dialysis products, the anticipated market acceptance and demand for NxStage’s products, anticipated increases in availability of and market and patient awareness regarding home and daily hemodialysis, and anticipated growth in the ESRD patient population. 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 including risks related to growth in home or more frequent hemodialysis, market acceptance and demand for NxStage’s products and certain other factors that may affect future operating results and which are detailed in NxStage’s filings with the Securities and Exchange Commission, including the Quarterly Report on Form 10-Q for the three months ended September 30, 2006.

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.

SOURCE NxStage Medical, Inc.

Kristen K. Sheppard, Esq.
Vice President, Investor Relations
NxStage Medical Inc. (NXTM)
Web site: http://www.nxstage.com
John K. Crawford, Chief Financial Officer
Linda M. Meador, Vice President, Human Resources
Both for Renal Advantage Inc.