EXHIBIT 99.2
 
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
                          TO BE HELD ON JUNE 24, 1998
 
TO THE STOCKHOLDERS OF WALSH INTERNATIONAL INC.:
 
    A special meeting of the stockholders (the "Special Meeting") of Walsh
International Inc., a Delaware corporation ("Walsh"), will be held on June 24,
1998 at 10:00 a.m., local time, at the offices of Reboul, MacMurray, Hewitt,
Maynard & Kristol, 45 Rockefeller Plaza, 11th floor, New York, New York for the
following purposes:
 
    1. To consider and vote upon a proposal to approve and adopt the Agreement
and Plan of Merger, dated as of March 23, 1998 (the "Merger Agreement"), among
Cognizant Corporation, a Delaware corporation ("Cognizant"), WAC Inc., a
Delaware corporation and a wholly owned subsidiary of Cognizant ("Merger Sub"),
and Walsh with respect to the merger of Merger Sub with and into Walsh upon the
terms and subject to the conditions thereof (the "Merger"). Pursuant to the
Merger Agreement, each share of common stock, par value $.01 per share, of Walsh
("Walsh Common Stock") issued and outstanding at the Effective Time of the
Merger (as defined in the accompanying Proxy Statement/ Prospectus), will be
converted into: (a) if the Effective Time of the Merger occurs prior to the
Cognizant Distribution Record Date (as defined in the accompanying Proxy
Statement/Prospectus), a fraction of a share of common stock, par value $.01 per
share, of Cognizant ("Cognizant Common Stock") determined by reference to the
average of the closing sale prices per share of Cognizant Common Stock on the
New York Stock Exchange Composite Transactions Tape on each of the 15
consecutive trading days immediately preceding the second trading day prior to
the Effective Time of the Merger; and (b) if the Effective Time of the Merger
occurs on or after the Cognizant Distribution Record Date, a fraction of a share
of common stock, par value $.01 per share ("IMS HEALTH Common Stock"), of IMS
Health Incorporated, a Delaware corporation ("IMS HEALTH"), determined by
reference to the average of the closing sale prices per share of IMS HEALTH
Common Stock on the New York Stock Exchange Composite Transactions Tape on each
of the 10 consecutive trading days immediately preceding the second trading day
prior to the Effective Time of the Merger. THE MERGER IS MORE COMPLETELY
DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS, AND A COPY OF THE
MERGER AGREEMENT IS ATTACHED AS ANNEX I THERETO.
 
    2. To transact such other business as may properly come before the Special
Meeting or any adjournments or postponements thereof.
 
    Only holders of record of shares of Walsh Common Stock at the close of
business on May 14, 1998, the record date for the Special Meeting, are entitled
to notice of, and to vote at, the Special Meeting and any adjournments or
postponements thereof.
 
    Each share of Walsh Common Stock will entitle the holder thereof to one vote
on each matter which may properly come before the Special Meeting. The
affirmative vote of the holders of a majority of the outstanding shares of Walsh
Common Stock is necessary to approve and adopt the Merger Agreement.
 
    WHETHER OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING, PLEASE COMPLETE, SIGN
AND DATE THE ENCLOSED PROXY CARD AND RETURN IT PROMPTLY IN THE ENCLOSED
POSTAGE-PAID ENVELOPE. PLEASE DO NOT SEND ANY STOCK CERTIFICATES AT THIS TIME.
YOUR PROXY MAY BE REVOKED AT ANY TIME BEFORE IT IS VOTED BY SIGNING AND
RETURNING A LATER DATED PROXY WITH RESPECT TO THE SAME SHARES, BY FILING WITH
THE SECRETARY OF WALSH A WRITTEN REVOCATION BEARING A LATER DATE OR BY ATTENDING
AND VOTING AT THE SPECIAL MEETING.
 
                                          By Order of the Board of Directors,
 
                                          /s/ Leonard R. Benjamin
 
                                          Leonard R. Benjamin
 
                                          Secretary
 
Dated: June 2, 1998