depot or long - acting antipsychotics confer better protection against psychotic relapse than their oral equivalents ( hogarty et al . , 1979 ; tiihonen et al . , conventional , or first generation , antipsychotic depots are widely used and have a low acquisition cost , but are associated with a high risk of tardive dyskinesia ( novick et al . , 2010 ) . in the last 10 years or so , several second - generation long - acting injections have been introduced . these formulations might be expected to provide at least as effective protection against relapse but with a lower risk of acute and chronic movement disorders ( leucht et al . , 1999 ) . however , there is only one controlled comparisons of conventional and atypical depots ( rubio et al . , 2006 )  a open randomized comparison of fairly high - dose risperidone with moderate doses of zuclopenthixol . a single randomized controlled trial against prescriber choice of oral medication found no benefit for risperidone long - acting injection on rehospitalization ( rosenheck et al . , 2011 ) . as a consequence , our understanding of the value of atypical depots is largely predicated on placebo - controlled regulatory studies and uncontrolled observational studies . observational studies of risperidone depot ( risperdal consta ) show that it is effective in some patient groups ( taylor et al . , 2009b ) , but also that its effect on time spent in hospital can be beneficial ( niaz and haddad , 2007 ; taylor et al . , 2008 ) , neutral ( taylor et al . , 2008 ) , or adverse [ in that some mirror - image studies show an increase in bed days after the initiation of risperidone depot ( young and taylor , 2006 ; taylor et al . , 2009a ) ] . we are engaged in a large - scale observational study of the most recently introduced atypical depot , paliperidone palmitate ( pp ) . here , we report on 1-year hospitalization outcomes for the first cohort of patients prescribed pp in our unit . its use was not restricted in any way but prescribers were required to complete data - gathering forms on initiation and cessation of pp . all patients prescribed pp were included in the study with the sole exception of  forensic patients ( whose stay in medium secure provision was governed by their sentence ) . this being an observational study , no attempt was made to influence decisions regarding the use of pp and patients received care as usual . demographic details were obtained for each patient from data forms and the electronic patient record . all adverse effects recorded were reported anonymously to janssen - cilag ltd ( buckinghamshire , uk ) , the manufacturer of pp . details of the time spent in hospital as inpatients were also obtained from electronic records . we recorded bed days for 3 years before starting pp and compared the mean yearly figure with the year following discharge from hospital having started pp ( inpatients ) or from the date of pp initiation ( outpatients ) . we also conducted sensitivity analysis comparing ( i ) the mean yearly bed days 3 years before the admission when pp was started with the year after discharge ( i.e. discarding all of the index admission ) , and ( ii ) the mean yearly bed days before and after pp initiation ( i.e. including all of the index admission ) . staff collecting data were those directly involved in the care of the individual patients . once entered on a communal database , all patient details were anonymized and the data files were secured . means and sds were calculated for continuous data and frequencies and percentages for categorical data . means and sds were calculated as a summary measure for admissions into hospital and associated bed days in the 3-year period before initiating pp . for continuous data not normally distributed , comparisons for admission rates and bed days before and after pp were performed using the nonparametric wilcoxon signed - rank test for paired data . all tests were performed using stata version 11.2 ( statacorp lp , college station , texas , usa ) . means and sds were calculated for continuous data and frequencies and percentages for categorical data . means and sds were calculated as a summary measure for admissions into hospital and associated bed days in the 3-year period before initiating pp . for continuous data not normally distributed , comparisons for admission rates and bed days before and after pp were performed using the nonparametric wilcoxon signed - rank test for paired data . all tests were performed using stata version 11.2 ( statacorp lp , college station , texas , usa ) . for those who initiated pp as inpatients , mean ( sd ) duration of current episode was 23.8 ( 53.8 ) days . sex , care setting and treatment responsiveness were not associated with admissions or hospital bed days following paliperidone initiation . details of discontinuation of pp during the year s follow - up are given in table 2 . 1 ) , the mean number of admissions reduced from 0.67/patient / year to 0.49/patient in the year following initiation / discharge on pp ( p=0.0001 ) ( fig . the mean bed days reduced from 38.78/patient / year to a mean of 23.09/patient / year ( p=0.0001 ) ( fig . improvements were numerically greater in those continuing on pp compared with those who discontinued ( tables 3 and 4 ) but statistically nonsignificant ( p=0.751 for change in admissions ; p=0.708 for change in bed days ) . pp , paliperidone palmitate . primary analysis of the mean number of admissions ( per patient / year ) . comparison of number of hospital admissions before and after paliperidone palmitate ( primary analysis ) primary analysis of the mean number of bed days spent in the hospital ( per patient / year ) . comparison of number of hospital bed days before and after paliperidone palmitate ( primary analysis ) sensitivity analyses generally suggested smaller benefits for pp . disregarding all of the index admissions ( fig . 4 ) , admissions for the total cohort fell from 0.53 ( sd 0.58)/patient / year to 0.49 ( 0.77)/patient / year ( p=0.014 ) . bed days reduced from a mean of 35.18 ( 50.41)/patient / year to 23.09 ( 49.82)/patient / year ( p=0.0001 ) . 5 ) , admissions fell from 0.67 ( 0.62)/patient / year to 0.51 ( 0.76)/patient / year ( p=0.0001 ) . bed days increased from a mean of 38.78 ( 51.83)/patient / year to 56.75 ( 78.60)/patient / year ( p=0.012 ) . schematic representation of the mirror image method sensitivity analysis   mirror at paliperidone palmitate ( pp ) initiation for all patients . in this 1-year follow - up of patients prescribed pp in normal clinical practice , the use of pp was associated with an important reduction in hospitalizations and days spent in hospital . pp was continued for a year after initiation in nearly two - thirds of patients and discontinuations because of adverse effects were uncommon . these broadly favorable clinical outcomes are important in determining the place of pp in therapy  a branded product with a much higher purchase cost than generic conventional depots . our observation that the use of pp reduces bed days by around 16/patient / year strongly supports the view that pp is likely to be cost - effective : its purchase cost ( close to  5000/year at maximum dose ) is outweighed by savings made on reduced hospitalizations ( estimated cost / day of uk psychiatric inpatient care is  338 ; 16 days is  5408 ) ( department of health , 2013 ) . our results in this study are in some contrast with our previous observations of outcomes associated with risperidone depot . in a similar study in our unit ( young and taylor , 2006 ; , 2009a ) the use of risperidone depot was associated with a very substantial increase in bed days in the first year after initiation . after 3 years , those initiated on risperidone depot had spent nearly double the time in hospital than they had spent 3 years before . included patients were broadly representative of our catchment area  including roughly equal numbers of men and women and the majority of patients being of african or african - caribbean descent . the improved outcome observed with pp here is unlikely to be a result of pharmacodynamic effects : paliperidone and risperidone have near identical pharmacological properties and risperidone is partly metabolized to paliperidone even after parenteral admission ( castberg and spigset , 2005 ; bowskill et al . , 2012 ) . it is more likely that the better outcomes are due to a number of factors combined : the facility to give loading doses of pp ; the use of relatively higher equivalent doses with pp ( the equivalent of 150 mg a month pp can not be given with risperidone ) ; and the broadly treatment - responsive nature of the patient cohort in this study [ in contrast to the risperidone study ( taylor et al . , 2006 ) ] . it is also notable that the lengthy oral supplementation period necessary with risperidone long - acting injection is likely to have a negative effect on bed stay . another factor might be that prescribers have , over time , become more adept at prescribing atypical long - acting injections and now choose those patients most likely to do well . also important in comparing the different results an analysis that also showed an increase in bed days , albeit a much smaller one than with risperidone . our ( a priori ) primary analysis is , we feel , more clinically realistic . it assumes that the period of hospitalization before pp initiation is a result of failure of the previously prescribed antipsychotic . the period between starting pp and discharge from hospital is the time during which pp begins to exert its therapeutic effect after the failure of prior therapy . although some might argue that one of our sensitivity analyses might be a better or farer method , it is notable that following discharge on pp the median bed days in the year after this is 0 . that is , at least half of the cohort spent no time in hospital in the year after discharge on pp  an important and somewhat unusual finding . we can not therefore assume or otherwise that pp is any better than any other drug . it also follows that improvement in outcomes observed after pp can not with certainty be attributed to the treatment as baseline trends in bed days and admissions were not established : something a control group would help to clarify . it is possible that changes in hospitalization rates were at least in part linked to changes in admission policies or in the availability of beds . also , without randomization we can not discount the likely positive effects of choosing pp for particular patients ( presumably responsive patients with a history of poor compliance ) . nonetheless , this does mean that our results are a sound reflection of practice , at least in our trust . overall , the use of pp in this cohort was broadly successful  the majority completed 1 year on pp and there was a reduction in both hospitalizations and the number of days spent in hospital . pp may thus be cost - effective in practice ; its use bringing about cost reductions greater than its purchase cost . three - year outcomes in our full cohort of over 500 patients will be essential in confirming or otherwise these observations . david taylor received research funding from eli lilly , servier and janssen and consultancy and/or lecturing honoraria from servier , janssen , roche , astrazeneca , lundbeck and otsuka .
paliperidone palmitate ( pp ) is a recently introduced long - acting atypical , or second - generation , antipsychotic . 
 published data on pp are currently limited to controlled trials and case reports . in this observational study , we followed up 200 consecutive patients prescribed pp in normal practice . 
 after 1 year , 65% of patients were still receiving pp . 
 the number of admissions to hospital in the year following pp initiation was 0.49/patient compared with 0.69/patient / year , 3 years before initiation ( p=0.0001 ) . 
 the mean number of bed days fell from 38.78 to 23.09/patient / year over the corresponding period ( p=0.0001 ) . the median number of bed days 3 years before pp initiation was 21.50/year and in the year following pp initiation , it was 0 . 
 outcomes were numerically but not statistically better in those continuing pp than in those who ceased pp within a year of initiation . 
 pp was effective and well - tolerated and , given its positive effect on hospital bed days , broadly cost - effective .