<PAGE>   1
                                                                   EXHIBIT 10.26


                           STOCK PURCHASE AGREEMENT

         This Stock Purchase Agreement ("Agreement") is made as of the 17th day
of April, 1998 by and between SIMIONE CENTRAL HOLDINGS, INC., a Delaware
Corporation (the "Company"), ECLIPSYS CORPORATION, a Delaware corporation (the
"Purchaser"), and the Stockholders listed on Schedule I attached hereto
(individually, a "Stockholder" and collectively, the "Stockholders").

Preliminary Statement

         A. The Stockholders own the shares (collectively, the "Shares") of the
common stock, $.00 1 par value per share (the "Common Stock"), of the Company
set forth opposite their respective names on Schedule I attached hereto.

         B. The Purchaser desires to purchase, and the Stockholders desire to
sell, the Shares for the consideration set forth below, subject to the terms and
conditions of this Agreement.

         C. It is in the interests of the Company to join in this Agreement in
connection with the execution of a reseller agreement and the grant of a right
in favor of the purchaser to acquire additional shares of Common Stock under
certain circumstances, each as provided herein.

         NOW, THEREFORE, in consideration of the mutual promises hereinafter set
forth and other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereby agree as follows:


         1.       Purchase and Sale of Shares from the Stockholders. Subject
to and upon the terms and conditions of this Agreement, each Stockholder shall
concurrently sell, and deliver to the Purchaser, and the Purchaser shall
purchase and accept from each Stockholder, the Shares set forth opposite such
Stockholder's name on Schedule I attached hereto at a price of $13.25 per share
for an aggregate purchase price of $5,565,000.

         2.       Closing Delivery.

                  (a)      The closing of the purchase and sale of the Shares
                           hereunder (the "Closing") shall be held at the
                           offices of the Purchaser, on the date hereof or at
                           such other time and place upon which the Company and
                           the Purchaser shall agree.

                  (b)      At the Closing, each Stockholder will deliver to the
                           Purchaser a certificate representing the Shares duly
                           endorsed in blank or with stock powers duty executed
                           by such Stockholder, and the Purchaser shall deliver
                           to the shareholders, the purchase price therefor due
                           to each Stockholder in cash, by cashier's or
                           certified check, or by wire transfer immediately
                           available funds to an account designated by the
                           Stockholder.



<PAGE>   2


                  (c)      At the Closing, the Company and the Purchasers shall
                           also enter into a Remarketing Agreement in the form
                           of Exhibit A attached hereto.

         3.       Representations and Warranties of the Company Regarding the
Company. The Company represents and warrants to the Purchaser as follows:

         (a)      The Company is a corporation duty organized, validly existing
                  and in good standing, under the laws of the jurisdiction of
                  its incorporation. No proceedings have been taken or
                  authorized by the Company or, to the best of the Company's
                  knowledge, by any other party, with respect to the bankruptcy,
                  insolvency, liquidation, dissolution or winding-up of the
                  Company.

         (b)(i)   The authorized capital stock of the Company consists of
                  20,000,000 shares of Common Stock and 10,000,000 shares of
                  Preferred Stock, $.001 par value per share ("Preferred
                  Stock"). As of March 31, 1998: (i) 8,524,478 shares of Common
                  Stock were issued and outstanding, all of which are validly
                  issued, fully paid and nonassessable; (ii) no shares of
                  Preferred Stock were issued or outstanding; (iii) no shares of
                  Common Stock or Preferred Stock were held in the treasury of
                  the Company or by subsidiaries of the Company; (iv) 186,079
                  shares were reserved for issuance under outstanding warrants
                  ("Warrants"); (v) 1,683,356 shares of Common Stock were
                  reserved for issuance pursuant to stock options granted and
                  outstanding as of March 31, 1998 and the plans or other
                  arrangements under which such options were granted (the
                  "Company Stock Plans"). The Shares, and all shares of Common
                  Stock subject to issuance as specified above, upon issuance on
                  the terms and conditions specified herein and in the
                  instruments pursuant to which they are issuable, shall be duly
                  authorized, validly issued, fully paid and nonassessable.
                  There are no obligations, contingent or otherwise, of the
                  Company or any of its subsidiaries to repurchase, redeem or
                  otherwise acquire any shares of Common Stock.

         (ii)     Except as reserved for grants of options or rights of
                  issuances of stock after March 31, 1998 under the Warrants
                  and Company Stock Plans and as disclosed on Schedule II, there
                  are no equity securities of any class of the Company or any of
                  its subsidiaries, or any security exchangeable into or
                  exercisable for such equity securities, issued, reserved for
                  issuance or outstanding. Except pursuant to the Warrants and
                  the Company's Stock Plans and as otherwise disclosed on
                  Schedule II, there are no options, warrants, equity
                  securities, calls, rights, commitments or agreements of any
                  character to which the Company or any of its subsidiaries is
                  a party or by which it is bound obligating the Company or any
                  of its subsidiaries to issue, deliver or sell, or cause to be
                  issued, delivered or sold, additional shares of capital stock
                  of the Company or any of its subsidiaries or obligating, the
                  Company or any of its subsidiaries to grant, extend or
                  accelerate the vesting of or enter into any such option,
                  warrant, equity security, call, right, commitment or
                  agreement, and, to the best knowledge of the Company, as of
                  the date of the Agreement, there are no



                                       2

<PAGE>   3


                  voting trust, proxies or other agreements or understandings
                  with respect to the shares of capital stock of the Company
                  except with respect to the Simione Central Holding, Inc.
                  Profit-Sharing Plan Trust and except as disclosed in the
                  Company's 1997 definitive proxy statement.

         (c)      The Company has all requisite power and authority to execute
                  and deliver this Agreement and to perform its obligations
                  hereunder. The execution and delivery of this Agreement by the
                  Company and the performance of this Agreement and the
                  consummation of the transactions contemplated hereby by the
                  Company have been duly and validly authorized by all necessary
                  corporate action on the part of the Company. This Agreement
                  has been duly and validly executed and delivered by the
                  Company and constitutes a valid and binding obligation of the
                  Company, enforceable against the Company in accordance with
                  its terms.

         (d)      Neither the execution and delivery of this Agreement by the
                  Company, nor the consummation by the Company of the
                  transactions contemplated hereby, will (i) conflict with or
                  violate any provision of the charter or By-laws of the
                  Company, (ii) require on the part of the Company any filing
                  with, or permit, authorization, consent or approval of, and
                  governmental entity, (iii) conflict with, result in a breach
                  of, constitute (with or without due notice or lapse of time or
                  both) a default under, result in the acceleration of, create
                  in any party any right to accelerate, terminate, modify or
                  cancel, or require any notice, consent or waiver under, any
                  contract, lease, sublease, license, sublicense, franchise,
                  permit, indenture, agreement or mortgage for borrowed money,
                  instrument of indebtedness, security interest or other
                  arrangement to which the Company is a party or by which either
                  is bound or to which any of their assets are subject, or (iv)
                  violate any order, writ, injunction, decree, status, rule or
                  regulation applicable to the Company or any of its properties
                  or assets.

         (e)      The Company has previously furnished to the Purchaser complete
                  and accurate copies, as amended or supplemented, of its (i)
                  Annual Report on Form 10-K for the fiscal year ended December
                  31, 1997, as filed with the Securities and Exchange Commission
                  ("SEC"), and (ii) all other reports filled by the Company
                  under Section 13 of the Exchange Act with the SEC since
                  December 11, 1997 (collectively, the "Company Reports"). As of
                  their respective dates, the Company Reports did not contain
                  any untrue statement of a material fact or omit to state a
                  material fact required to be stated therein or necessary to
                  make the statements therein, in light of the circumstances
                  under which they were made, not misleading. The audited
                  financial statements and unaudited interim financial
                  statements of the Company included in the Company Reports (i)
                  comply as to form in all material respects with applicable
                  accounting requirements and the published rules and
                  regulations of the SEC with respect thereto, (ii) have been
                  prepared in accordance with GAAP applied on a consistent basis
                  throughout the periods covered thereby (except as may be
                  indicated therein or in the notes thereto, and in the case of
                  quarterly financial statements, as permitted by Form 10-Q
                  under the Exchange Act) and (iii) fairly 



                                       3
<PAGE>   4
                  present the consolidated financial condition, results of
                  operations and cash flows of the Company as of the respective
                  dates thereof and for the periods referred to therein
                  (subject, in the case of unaudited statements, to normal
                  recurring year-end adjustments).

         (f)      Since December 31, 1997, to the Company's knowledge, there has
                  not been any material adverse change in the assets, business,
                  financial condition or results of operations or future
                  prospects of the Company.

         (g)      The Company has no liability or obligation to pay any fees or
                  commissions to any broker, finder or agent with respect to the
                  transactions contemplated by this Agreement.

         (h)      Except as disclosed in the Company Reports, there is no (i)
                  unsatisfied judgment, order, decree, stipulation or injunction
                  or (ii) claim, complaint action, suit, proceeding, hearing or
                  investigation of or in any governmental entity before any
                  arbitrator to which the Company is a party or, to the
                  Company's knowledge, threatened to be made a party, that could
                  reasonably be expected to have a material adverse effect on
                  the assets, business, financial condition, results of
                  operations or future prospects of the Company.

         4.       Representations of the Stockholders Regarding the Shares. Each
Stockholder represents and warrants to the Purchaser as follows:

         (a)      Such Stockholder has good and marketable title to the Shares
                  which are to be transferred to the Purchaser by such
                  Stockholder pursuant here, to, free and clear of any and all
                  covenants, conditions, restrictions (other than under the
                  Securities Act, as hereinafter defined), voting, trust
                  arrangements, liens, charges, encumbrances, options and
                  adverse claims or rights whatsoever.

         (b)      Such Stockholder has the full right, power and authority to
                  enter into this Agreement and to transfer, convey and sell to
                  the Purchaser at the Closing the Shares to be sold by such
                  Stockholder hereunder and, upon consummation of the purchase
                  contemplated hereby, the Purchaser will acquire from such
                  Stockholder good and marketable title to such Shares, free and
                  clear of all covenants, conditions, restrictions (other than
                  under the Securities Act, as hereinafter defined, or
                  hereunder), voting, trust arrangements, liens, charges,
                  encumbrances, options and adverse claims or rights whatsoever.

         (c)      Such Stockholder is not a party to, subject to or bound by any
                  agreement or any judgment, order, writ, prohibition,
                  injunction or decree of any court or other governmental body
                  which would prevent the execution or delivery of this
                  Agreement by such Stockholder or the transfer, conveyance and
                  sale of the Shares to be sold by such Stockholder to the
                  Purchaser pursuant to the terms hereof.



                                       4
<PAGE>   5


         (d)      No broker or finder has acted for such Stockholder in
                  connection with this Agreement or the transactions
                  contemplated hereby, and no broker or finder is entitled to
                  any brokerage or finder's fee or other commissions in respect
                  of such transactions based upon agreements, arrangements or
                  understandings made by or on behalf of such Stockholder.

         5.       Company Board of Directors. So long as this Agreement
                  continues in effect:
  
         (a)      The Purchaser shall have the right to designate a
                  representative reasonably acceptable to the Company's Board of
                  Directors for election as a Director. Pursuant to such right,
                  at the next regularly scheduled meeting, of the Company's
                  Board of Directors after receiving notice from the Purchaser
                  that it has elected to designate a representative to serve on
                  the Board, the Company shall expand its Board of Directors by
                  one Director and shall appoint such nominee representative to
                  fill the vacant directorship created by such expansion. The
                  Company represents to the Purchaser that pursuant to its
                  By-laws, as currently in effect, its Board of Directors has
                  the authority, without further action by its shareholders, to
                  effect such expansion in the number of the Company's Directors
                  and to fill the vacancy created by such expansion.

         (b)      Such representative shall excuse himself or herself from
                  voting in any portion of any meeting relating to the
                  consideration of any matter in which Purchaser has a material
                  interest, other than solely as a stockholder.

         (c)      Prior to the next regular meeting of the Company's
                  shareholders after appointment of any such Purchaser
                  representative to the Board and thereafter prior to all
                  meetings of the Company's shareholders at which Directors will
                  be elected, the Company shall nominate and recommend the
                  Purchaser representative (or a successor reasonably acceptable
                  to the Company's Board of Directors) for election to a seat
                  on the Company's Board of Directors, and shall use its best
                  efforts to cause such Purchaser representative to be elected
                  as such Director. In the event that this Agreement shall
                  terminate as provided in Section 8 below, no such termination
                  shall preclude the Purchaser from thereafter voting those
                  shares that then have the right to vote on Directors of the
                  Company for election of a Purchaser representative to the
                  Company's Board. At any time upon written request of the
                  Company following the termination of this Agreement,
                  Purchaser shall cause the Purchaser's representative to resign
                  from the Company's Board of Directors.

         (d)      Purchaser shall take such action as may be required so that
                  all Shares are voted for nominees to the Board of Directors of
                  the Company, and unless the Company otherwise consents in
                  writing, on all other matters to be voted on by holders of the
                  Common Stock, in favor of all such matters recommended by the
                  Company's Board of Directors.



                                       5
<PAGE>   6


         (e)      Notwithstanding the provisions of this Section 5, the Company
                  shall not be obligated to nominate or appoint any person to
                  the Company's Board of Directors who (i) in the written
                  opinion of outside counsel, would not be qualified under
                  applicable law, rule or regulation to serve as a director of
                  the Company, or (ii) has been involved in any of the events
                  enumerated in Item 2(d) or (c) of Schedule 13D promulgated
                  under the Securities Exchange Act of 1934, or who is the
                  target of an investigation by any governmental authority or
                  agency relating to felonious criminal activity, or subject to
                  any order, decree or judgment of any court or agency
                  prohibiting service as a director of any public company or
                  providing investment or financial advisory services.

         6.       Covenants.

         (a)      Purchaser agrees that neither the Purchaser nor any of its
                  affiliates, alone or with others, will in any mariner acquire,
                  agree to acquire, make any proposal (or request permission to
                  make any proposal) to acquire any securities (or direct or
                  indirect rights, warrants or options to acquire any
                  securities) of the Company (other than securities constituting
                  less than 1% of the outstanding Common Stock of the Company
                  or securities issued as a dividend or distribution upon the
                  Shares), unless such acquisition, agreement or making of a
                  proposal shall have been first approved (or in the case of a
                  proposal, first invited) by the Company's Board of Directors.

         (b)(i)   In the event that at any time on or before 180 days of the
                  date of this Agreement, the Company proposes to enter into any
                  agreement for merger or consolidation of the Company, a sale
                  or disposition of 50% or more of its assets or earning power,
                  or issuance of additional equity securities, as a result of
                  which the other party or parties to such agreement would
                  thereafter own, directly or indirectly, a substantial portion
                  of the Company's business or a majority of the outstanding
                  Voting Stock of the Company (any of the foregoing, an
                  "Acquisition Event"), the Company shall provide the Purchaser
                  written notice of such Acquisition Event at least 20 days
                  prior to entering into a definitive agreement for any such
                  Acquisition Event, which notice shall contain a description of
                  the general nature of the proposed transaction.

         (ii)     The Company shall also provide the Purchaser prompt written
                  notice:

                  (A)     of all bona fide offers it receives to purchase more
                          than 5% of its outstanding Voting Stock or acquire a
                          substantial portion of its assets or business;

                  (B)     if the Company receives notice that a third party
                          has purchased or made an offer to purchase 5% or more
                          of its outstanding Voting Stock or reasonably believes
                          there is a substantial possibility that a third party
                          intends to purchase, or to make an offer to purchase
                          more than 5% of its outstanding Voting Stock; and



                                       6

<PAGE>   7


                  (C)      if the Company intends to enter into a definitive
                           agreement to sell additional shares of its Voting
                           Stock comprising more than 5% of its outstanding 
                           Voting Stock.

         (iii)    Upon the receipt by Purchaser of written notice pursuant to
                  clause (b)(1) above, the Purchaser shall have the right,
                  exercisable by written notice delivered within twenty (20)
                  days to the Company, to acquire, on the closing date of the
                  Acquisition Event ("Notified Closing Date") up to that number
                  of shares of Common Stock equal to 4.9% of the outstanding
                  Common Stock of the Company on the Notified Closing Date at a
                  purchase price of $13.25 a share, which acquisition shall be
                  effected on the Notified Closing Date in accordance with the
                  procedures of Section 2(b) above.

         7.       Investment Representation. The Purchaser represents, warrants
and covenants as follows:

         (a)      It is purchasing the shares for investment only, and not with
                  a view to, or for sale in connection with, any distribution of
                  the Shares in violation of the Securities Act of 1933 (the
                  "Securities Act"), or any rule or regulation under the
                  Securities Act.

         (b)      It has had such opportunities as it deems adequate to obtain
                  from representatives of the Company such information as is
                  necessary to permit it to evaluate the merits and risks of
                  investment in the Company.

         (c)      It can afford a complete loss of the value of the Shares and
                  is able to bear the economic risk of holding such Shares for
                  an indefinite period.

         (d)      It understands that (i) the Shares have not been registered
                  under the Securities Act and are "restricted securities"
                  within the meaning of Rule 144 under the Securities Act, (ii)
                  the Shares cannot be sold, transferred or otherwise disposed
                  of unless they are subsequently registered under the
                  Securities Act or an exemption from registration is then
                  available; (iii) in any event, the exemption from registration
                  under Rule 144 or otherwise may not be available for at least
                  one year and even then will not be available unless a public
                  market then exists for the Common Stock, adequate information
                  concerning the Company is then available to the public, and
                  other terms and conditions of Rule 144 are complied with; and
                  (iv) there is now no registration statement on file with the
                  securities and Exchange Commission with respect to any stock
                  of the Company and the Company has no obligation or current
                  intention to registered the Shares under the Securities Act.

         (e)      A legend substantially in the following form will be placed on
                  the certificate representing the Shares:

                           "The shares represented by this certificate have not
                           been registered under the Securities Act of 1933, as
                           amended, and may not be sold, transferred or



                                       7

<PAGE>   8


                           otherwise disposed of in the absence of an effective
                           registration statement under such Act or an opinion
                           of counsel satisfactory to the corporation to the
                           effect that such registration is not required."

         (f)      In the event of any purchase of Common Stock pursuant to
                  Section 6(b)(iii) above, the Purchaser shall make the
                  foregoing representations with respect to the Common Stock
                  purchased on the Notified Closing Date.

         8.       Term. This Agreement shall continue in effect until the
                  earlier of (i) April 17, 2001, or (ii) the date on which the
                  Remarketing Agreement terminates.

         9.       Miscellaneous.

         (a)      The parties agree to execute such further instruments and to
                  take such further action as may reasonably be necessary to
                  carry out the intent of this agreement.

         (b)      For purposes of this Agreement, and for all notices and
                  correspondence hereunder, the addresses of the respective
                  parties are as follows:

                           If to Purchaser:

                           Eclipsys Corporation
                           777 East Atlantic Avenue, Suit 200
                           Delray Beach, FL 33483
                           Attention: Harvey Wilson, Chief Executive Officer

                           With a copy to:

                           John A. Burgess, Esq.
                           Hale and Dorr LLP
                           60 State Street
                           Boston, MA 02109

                           If to Company:

                           Simione Central Holdings, Inc.
                                            
                           6600 Powers Ferry Road
                           Atlanta, GA 30339
                           Attention: James R. Henderson, President and CEO

                           With a copy to:

                           Simione Central Holdings, Inc.


                                       8


<PAGE>   9


                           6600 Powers Ferry Road
                           Atlanta, GA 30339
                           Attention: General Counsel

                           If to the Stockholders:

                           Gary M. Bremer
                           Gary B. Bremer
                           William T. Simione, Jr.
                           c/o Simione Central Holdings, Inc.
                           6600 Powers Ferry Road                     
                           Atlanta, GA 30339                          
                                                                      
                           Rod D. Windley                             
                           c/o Heathfield, Inc.                       
                           6666 Power Ferry Road, 3rd Floor           
                           Atlanta, GA 30339                          
                           
                  No change of address shall be binding upon the other party
                  hereto until written notice thereof is received by such party
                  at the address shown herein. All notices shall be in English
                  and shall be effective upon receipt if delivered personally,
                  two days after shipment by overnight delivery services and
                  seven (7) days after mailing if sent by mail.

         (c)      This Agreement shall be governed by the taws of the State of
                  Delaware and interpreted and determined in accordance with the
                  laws of the State of Delaware courts to contracts made and to
                  be performed entirely in Delaware by residents of that state.

         (d)      This Agreement shall inure to the benefit of the successors
                  and assigns of the Company and the Purchaser.

         (e)      In the event that any provision of this Agreement becomes or
                  is declared by a court of competent jurisdiction to be
                  illegal, unenforceable or void, this Agreement shall continue
                  in full force and effect without said provision.

         (f)      This Agreement constitutes the entire agreement of the parties
                  with respect to the subject matter hereof and may not be
                  amended except in a writing signed by each party hereto.

         (g)      This Agreement may be executed in counterparts, each of which
                  shall be deemed an original, but all of which shall constitute
                  the same instrument.



                                       9

<PAGE>   10


          IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year first above written.

ATTEST:                                 PURCHASER:

                                        Eclipsys Corporation

                                        By: /s/
--------------------------------           ------------------------------------
                                           Vice President

ATTEST:                                 THE COMPANY:

                                        Simione Central  Holdings, Inc.

                                        By: /s/
--------------------------------           ------------------------------------
                                           COO

                                        STOCKHOLDERS:

                                        Gary M. Bremer


                                        ----------------------------------------

                                        Gary B. Bremer


                                        ----------------------------------------

                                        William J. Simione, Jr.


                                        ----------------------------------------

                                        Rod D. Windley

                                         /s/ R.D. Windley
                                        ----------------------------------------


                                       11

<PAGE>   11


                            SCHEDULE I

Stockholders                                     Shares To Be Sold

Gary M. Bremer                                        187,500

Gary B. Bremer                                        20,000

William J. Simione, Jr.                               25,000

Rod D. Windley                                        187,500



                                       12

<PAGE>   12


                                   SCHEDULE II

(1)      Offer to issue shares of its Common Stock for $8,000,000 of the
         proposed purchase price in an acquisition transaction. The purchase
         price to be based upon the value of the Company's Common Stock at the
         execution of a definitive agreement in connection with such proposed
         acquisition.

(2)      Effective April 15, 1998, the Company merged InfoMed, Inc. into its
         wholly-owned subsidiary Simione Central National, Inc. and in
         connection with this merger, the Company issued 6,844 shares of its
         Common Stock to the remaining minority shareholders of InfoMed, Inc.

(3)      The Board of Directors has approved, subject to shareholder approval,
         an increase in the number of shares available for grant of stock
         options of 1,000,000 shares under the Company's 1997 Stock Plan.
         Options for 344,725 shares have been granted by the Compensation
         Committee subject to shareholder approval to total share increase.





                                       
                                       13