***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: BACKGROUND Patients with human immunodeficiency virus ( HIV ) infection and a history of Pneumocystis carinii pneumonia are at high risk for relapse if they are not given secondary prophylaxis . Whether secondary prophylaxis against P. carinii pneumonia can be safely discontinued in patients who have a response to highly active antiretroviral therapy is not known . METHODS We analyzed episodes of recurrent P. carinii pneumonia in 325 HIV-infected patients ( 275 men and 50 women ) in eight prospect i ve European cohorts . Between October 1996 and January 2000 , these patients discontinued secondary prophylaxis during treatment with at least three anti-HIV drugs after they had at least one peripheral-blood CD4 cell count of more than 200 cells per cubic millimeter . RESULTS Secondary prophylaxis was discontinued at a median CD4 cell count of 350 per cubic millimeter ; the median nadir CD4 cell count had been 50 per cubic millimeter . The median duration of the increase in the CD4 cell count to more than 200 per cubic millimeter after discontinuation of secondary prophylaxis was 11 months . The median follow-up period after discontinuation of secondary prophylaxis was 13 months , yielding a total of 374 person-years of follow-up ; for 355 of these person-years , CD4 cell counts remained at or above 200 per cubic millimeter . No cases of recurrent P. carinii pneumonia were diagnosed during this period ; the incidence was thus 0 per 100 patient-years ( 99 percent confidence interval , 0 to 1.2 per 100 patient-years , on the basis of the entire follow-up period , and 0 to 1.3 per 100 patient-years , on the basis of the follow-up period during which CD4 cell counts remained at or above 200 per cubic millimeter ) . CONCLUSIONS It is safe to discontinue secondary prophylaxis against P. carinii pneumonia in patients with HIV infection who have an immunologic response to highly active antiretroviral therapy This subgroup analysis assessing secondary prophylaxis for Pneumocystis carinii pneumonia ( PCP ) describes a multicenter , open-labeled , r and omized , controlled trial evaluating the discontinuation of PCP prophylaxis . The main inclusion criterion was a history of PCP and an increase in the CD4 cell count to > 200 cells/microL associated with receipt of highly active antiretroviral therapy for > or=3 months . The primary end point was the development of definitive or presumptive PCP . A total of 146 patients were enrolled ( 77 in the treatment discontinuation arm ) . After > 2 years , 1 definitive and 1 presumptive case of PCP were observed , both of which occurred in patients who discontinued therapy . In most patients , secondary prophylaxis for PCP can be safely discontinued after potent antiretroviral therapy is initiated , but the threshold of > 200 CD4 cells/microL may not be considered absolutely safe . Patients who present with symptoms after discontinuation of secondary prophylaxis  should be evaluated for PCP despite high CD4 count and complete virus suppression BACKGROUND Prophylactic drugs for Pneumocystis carinii pneumonia ( PCP ) are strongly recommended for HIV-1-infected patients with CD4 cell counts of less than 200 cells/microL. Because of the highly active antiretroviral therapy ( HAART ) currently available , we speculated that prophylaxis can be discontinued in patients with CD4 cell counts of more than 200 cells/microL. METHODS In this prospect i ve observational study , PCP prophylaxis ( primary or secondary ) was discontinued in HIV-1-infected patients whose CD4 cell count had increased above 200 cells/microL ( documented twice with an interval of at least 1 month ) as a result of HAART .  Patients and their CD4 cell counts were monitored every 3 months . The primary endpoint of the study was the occurrence or reoccurrence of PCP . FINDINGS 78 patients were enrolled : 62 patients were receiving prophylaxis for primary prevention of PCP and 16 patients for secondary prevention of PCP . At the time of discontinuation of prophylaxis , the mean CD4 cell count was 347 cells/microL , and HIV-1-RNA was not detectable in 61 patients . The lowest mean CD4 cell count during prophylaxis was 79 cells/microL. Patients stopped prophylaxis 9.8 ( SD 6.4 ) months after they started HAART . The mean follow-up after discontinuation of prophylaxis was 12.7 ( SD 7.6 ) months , and none of the patients developed PCP ( 97.5 % one-sided CI 0 - 4.4 % ) . INTERPRETATION The preliminary results of this study indicate that PCP prophylaxis can be stopped safely in HIV-1-infected patients whose CD4 cell counts have increased above 200 cells/microL after treatment with HAART OBJECTIVES To analyse the incidence of Pneumocystis carinii pneumonia after the withdrawal of prophylaxis , in patients with AIDS who were receiving HAART ( highly active antiretroviral treatment ) .  PATIENTS AND METHODS Prospect i ve opened study of 85 patients with AIDS ( CD4 lymphocytes < 200 x 10(6)/l ) and whose CD4 counts had increased over 200 x 10(6)/l after HAART , 79 were under primary prophylaxis and six secondary . RESULTS Mean CD4 lymphocytes count at the time of withdrawal was 343 x 10(6)/l . Mean time of follow-up after withdrawal was 358 days ( range : 93 - 1,487 ; median : 302 ) . None of the patients have had Pneumocystis carinii or toxoplasmosis after withdrawal of prophylaxis . CONCLUSIONS Pneumocystis carinii prophylaxis in AIDS patients might be safety withdrawn after effective HAART Highly active antiretroviral therapy ( HAART ) has substantially affected the care and the disease course of HIV-infected patients . In the HIV Outpatient Study ( HOPS ) , a study of ambulatory HIV-infected patients in HIV clinics across the United States , we have observed several phenomena related to the use of HAART .  Mortality and morbidity rates have declined remarkably and substantially in this population with the advent of more effective antiretroviral therapies ( 1 ) , but the typical patient must take an average of 13 pills per day to maintain a good virologic and immunologic result ( 2 ) . Meanwhile , as CD4 + lymphocyte counts have increased in treated patients , the incidence of Pneumocystis carinii pneumonia ( PCP ) has declined dramatically ( 1 , 3 ) . Given the low incidence of PCP , the occasional toxicity of PCP chemoprophylaxis , and the numerous pills that ambulatory HIV patients receive , many HIV clinicians have begun cautiously discontinuing PCP prophylaxisnormally trimethoprim-sulfamethoxazole given three or more times per weekamong patients who have sustained immunologic and virologic responses to HAART . In this study , we sought to determine whether discontinuing PCP prophylaxis in HOPS patients who had sustained CD4 + cell counts greater than 200 cells/mm3 changed the rates of development of PCP compared with patients who continued PCP prophylaxis . Methods The methods used in HOPS , a dynamic cohort study , have been described elsewhere ( 1 , 4 ) . This continuously recruiting study now includes prospect i ve , electronically collected summaries of physicianpatient interactions and the course of disease for more than 4800 HIV-infected ambulatory patients seen in more than 82 000 outpatient visits since 1992 . Our analysis included persons who visited a HOPS site from June 1995 through December 1998 . Our study sites were 10 HIV clinics , of which 8 were private and 2 were public , in 8 U.S. cities : Tampa , Florida ; Washington , D.C. ; Denver , Colorado ; Portl and , Oregon ; Oakl and , California ; Chicago , Illinois ; Stony Brook , New York ; and Philadelphia , Pennsylvania . Of the 12 HOPS physicians , 11 are board-certified in internal medicine and infectious diseases ; these physicians routinely care for hundreds of HIV-infected patients every year and thus are experienced HIV caregivers . Information in five general categories is abstract ed from each patient visit by trained study staff and is electronically entered in a common data collection system that spans the time of observation . Data are collected central ly , and they are review ed and corrected before being added to the data base . The five categories of information are demographic characteristics and risk behaviors for HIV infection ; symptoms ; diagnosed diseases ( definitive and presumptive ) ; prescribed medications , including dosage and duration ; and laboratory values , including CD4 + lymphocyte counts and viral loads ( HIV RNA copies/mL of plasma ) . In this analysis , we assessed patients whose CD4 + cell counts increased from 200 cells/mm3 or less to greater than 200 cells/mm3 after antiretroviral therapy ( HAART was being given in more than 80 % of patients by 1998 [ 1 ] ) and who were nonr and omly chosen by their clinicians to discontinue or continue PCP prophylaxis .  The observation periods for all patients who had two consecutive cell counts greater than ( that is , sustained higher than ) 200 CD4 + cells/mm3 started when they first had a CD4 + cell count greater than 200 cells/mm3 . We compared the demographic ( age , sex , race or ethnicity , geographic site , HIV risk group , education level , and insurance or payment source ) , clinical ( previous PCP , other opportunistic infections , and AIDS diagnosis ) , immunologic ( CD4 + cell count , including lowest and highest ) , and most recent virologic ( copies of HIV RNA [ viral load ] ) characteristics of patients who either discontinued or continued PCP prophylaxis .  Data collected in the HOPS were analyzed by using SAS software , version 6.0 ( SAS Institute , Inc. , Cary , North Carolina ) , and EpiInfo , version 6.04 ( Centers for Disease Control and Prevention , Atlanta , Georgia ) . We calculated , by using an exact binomial test , the upper confidence limits for ( zero ) PCP incidence in patients who discontinued and those who continued prophylaxis . The characteristics of those who discontinued PCP prophylaxis were compared with the characteristics of those who continued it by using the chi-square test or Wilcoxon rank-sum test , as appropriate . The HOPS as a whole and this sub study are funded entirely by the Centers for Disease Control and Prevention . Results Of patients who maintained CD4 + lymphocyte counts greater than 200 cells/mm3 , 146 who discontinued PCP prophylaxis were followed for a mean of 18.2 months ( 221.4 total person-years ) and 345 who continued PCP prophylaxis were followed for a mean of 14.0 months ( 402.5 total person-years ) ( Table 1 ) . Patients and their physicians were more likely to discontinue PCP prophylaxis in succeeding calendar years of the study ( data not shown ) . Neither patients who discontinued nor those who continued PCP prophylaxis acquired definitive or presumptive PCP ( upper 95 % exact binomial confidence limits , 2.3/100 person-years for patients who discontinued prophylaxis and 1.3/100 person-years for patients who continued prophylaxis ) . Table 1 . Demographic and Clinical Characteristics of Patients Who Discontinued and Those Who Continued Pneumocystis carinii Pneumonia Chemoprophylaxis Toxoplasmosis  did not occur in either group . Bacterial infections , such as pneumonia , sinusitis , bronchitis , and urinary tract infections , occurred somewhat less often in patients who discontinued PCP prophylaxis ( 18.6 % ) than in those who continued PCP prophylaxis ( 28.3 % ) , but the difference was not significant ( Yates-corrected chi-square test , P=0.14 ) . Compared with patients who continued PCP prophylaxis , more of those who discontinued prophylaxis were white than belonged to any other racial or ethnic groups , and fewer of these patients had had a previous episode of PCP ( Table 1 ) . The median patient age did not significantly differ between the group that discontinued PCP prophylaxis and the group that continued PCP prophylaxis ( median , 39.2 years compared with 39.9 years ; Wilcoxon test , P=0.2 ) . We also analyzed the insurance ( payer ) status of patients ; no significant differences were seen in care between the two groups , whether their care was compensated by the patient , private insurance , public insurance , or assistance such as Medicare and Medicaid ( data not shown ) . Of patients discontinuing PCP prophylaxis , 75 % were receiving  protease inhibitor-based antiretroviral therapy  at the time of discontinuation , but this percentage did not differ from rates of protease inhibitor use in the HOPS cohort in the same years ( 1 ) . According to laboratory data , patients who discontinued PCP prophylaxis had a significantly higher CD4 + cell nadir ( lowest recorded CD4 + cell count ) , a higher acme ( highest recorded CD4 + cell count ) , a longer period during which CD4 + cell counts were greater than 20 
    Output:
    
In one study in which individuals were stratified according to CD4 count < 200 cells/µL , there was a greater risk of PCP with CD4 count ≤100 cells/µL compared to 101–200 cells/µL. Conclusion Primary PCP prophylaxis may be safely discontinued in HIV-infected individuals with CD4 count between 101–200 cells/µL provided the VL is fully suppressed on antiretroviral therapy .