Determining sample size for progression criteria for pragmatic pilot RCTs: the hypothesis test strikes back!

Background

The current CONSORT guidelines for reporting pilot trials do not recommend hypothesis testing of clinical outcomes on the basis that a pilot trial is under-powered to detect such differences and this is the aim of the main trial. It states that primary evaluation should focus on descriptive analysis of feasibility/process outcomes (e.g. recruitment, adherence, treatment fidelity). Whilst the argument for not testing clinical outcomes is justifiable, the same does not necessarily apply to feasibility/process outcomes, where differences may be large and detectable with small samples. Moreover, there remains much ambiguity around sample size for pilot trials.

Methods

Many pilot trials adopt a ‘traffic light’ system for evaluating progression to the main trial determined by a set of criteria set up a priori. We construct a hypothesis testing approach for binary feasibility outcomes focused around this system that tests against being in the RED zone (unacceptable outcome) based on an expectation of being in the GREEN zone (acceptable outcome) and choose the sample size to give high power to reject being in the RED zone if the GREEN zone holds true. Pilot point estimates falling in the RED zone will be statistically non-significant and in the GREEN zone will be significant; the AMBER zone designates potentially acceptable outcome and statistical tests may be significant or non-significant.

Results

For example, in relation to treatment fidelity, if we assume the upper boundary of the RED zone is 50% and the lower boundary of the GREEN zone is 75% (designating unacceptable and acceptable treatment fidelity, respectively), the sample size required for analysis given 90% power and one-sided 5% alpha would be around n = 34 (intervention group alone). Observed treatment fidelity in the range of 0–17 participants (0–50%) will fall into the RED zone and be statistically non-significant, 18–25 (51–74%) fall into AMBER and may or may not be significant and 26–34 (75–100%) fall into GREEN and will be significant indicating acceptable fidelity.

Discussion

In general, several key process outcomes are assessed for progression to a main trial; a composite approach would require appraising the rules of progression across all these outcomes. This methodology provides a formal framework for hypothesis testing and sample size indication around process outcome evaluation for pilot RCTs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-021-00770-x.

Cardiorespiratory fitness fails to predict short-term postoperative mortality in patients undergoing elective open surgery for abdominal aortic aneurysm

INTRODUCTION

Preoperative cardiopulmonary exercise testing aids surgical risk stratification and is an established predictor of mid- to long-term survival in patients undergoing elective open abdominal aortic aneurysm repair. Whether cardiopulmonary exercise testing also predicts 30-day mortality in this population remains to be established.

MATERIALS AND METHODS

Data for 109 patients (mean age 72 years) who underwent cardiopulmonary exercise testing to assess risk for surgical abdominal aortic aneurysm repair was analysed. Patients were classified according to cardiopulmonary fitness as fit (peak oxygen uptake ≥ 15ml O₂.kg^-1.min^-1) or unfit (peak oxygen uptake less than 15ml O₂.kg^-1.min^-1) and further stratified according to clamp position (infrarenal or suprarenal). Between-group postoperative outcomes were compared for in-hospital 30-day mortality, postoperative morbidity scale scores (day 5) and hospital length of stay.

RESULTS

Seventy-nine patients underwent open surgery and 30 patients were treated conservatively. No deaths were recorded at 30 days post-surgery. Unfit patients with infrarenal clamping exhibited higher postoperative morbidity scale scores (64% vs 26%) and longer length of stay (four days) than fit patients (p < 0.05). Conversely, with suprarenal clamping, postoperative morbidity scale scores were similar and length of stay longer (three days) in fit compared with unfit patients (p < 0.05).

DISCUSSION AND CONCLUSION

Preoperative fitness level defined by peak oxygen uptake failed to identify patients at risk of 30-day mortality when undergoing elective abdominal aortic aneurysm repair. Postoperative morbidity and length of stay in patients with suprarenal clamping was high independent of cardiopulmonary fitness. These findings suggest that cardiopulmonary exercise testing may be a useful predictor of complications following infrarenal rather than suprarenal clamping but may not be a good predictor of 30-day mortality.

THU0082 MERTK SYNOVIAL EXPRESSION CORRELATES WITH TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS

Background:

Despite substantial improvements in long-term clinical outcomes, a significant proportion of rheumatoid arthritis (RA) patients still fail to respond to treatment adequately, and early prognostic biomarkers of response are missing. Single-cell transcriptomic studies on RA synovial tissue (ST) have shown that MerTK is highly expressed in “anti-inflammatory” macrophages [1]. It has also been suggested that synovial macrophages isolated from RA patients in remission are characterised by a CD206+/MerTK+ signature [2]. Finally, monocyte-derived macrophages from RA patients treated with TNF-inhibitors (TNF-i) up-regulate MerTK.

Objectives:

To assess i) the modulation of synovial tissue MerTK+ macrophages upon treatment with conventional synthetic (cs) disease-modifying anti-rheumatic drugs (DMARDs) and ii) the relationship between baselineMerTKgene expression and response to TNFi.

Methods:

ST was obtained by US-guided synovial biopsies of an inflamed peripheral joint in patients with early (<12 months) treatment-naïve RA (as per ACR/EULAR 2010 criteria). A second biopsy of the same joint was repeated six months after starting treatment with single or multiple csDMARDs. ST (n=15) was stained for CD68, MerTK and CD206 by immunofluorescence using a tyramide amplification signal system. Quantification of the percentage of single- (MerTK+ or CD206+) and double-positive (CD206+MerTK+) CD68+ macrophages was obtained by digital image analysis (Image J). Gene expression analysis was performed on RNA sequences of 22 baseline ST samples (treatment-naïve).

Results:

Before any treatment intervention, the percentage of MerTK+CD206+ macrophages was significantly higher in RA patients with low (DAS28<3.2) versus high (DAS28>5.1) disease activity (24.5±20.1 versus 4.8±4.8, p<0.05). There were no differences in the relative number of MerTK+ or CD206+ or MerTK+CD206+ macrophages at baseline in relationship with the clinical response to csDMARDs at 6-months. On the other hand, patients (n=5) achieving remission (DAS<2.6) upon receiving csDMARDs significantly increased the number of MerTK+ macrophages from pre- to six-months post-treatment (23.6±23.8 to 55.5±15.4, p<0.05) in comparison with patients (n=5) who were still active after treatment (18±15.6 to 30.4±11.17, p=ns). MerTK synovial gene expression at baseline (i.e., in newly diagnosed treatment-naïve RA patients) was significantly higher in patients subsequently treated with TNFi and achieving a good/moderate EULAR response at 12 months in comparison with those who did not respond (n=14, n=8, p adjusted 0.003).

Conclusion:

Our whole-tissue protein expression data further support the hypothesis that a selective expansion of the MerTK+ macrophage subset characterise patients achieving remission. Moreover, the pre-treatment up-regulation of the MerTK gene in future responders to TNFi suggest that MerTK is implicated in modulating synovial inflammatory responses and may be exploited as a therapeutic target in RA.

References:

[1]F. Zhang et al, Nature Immunology, vol. 20, no. 7, pp. 928–942, 2019.

[2]S. R. Finlay at al, Annals of the Rheumatic Diseases, vol. 77, Supplement 2, pp. 183–183, 2018.

[3]Y. Degboé et al, Frontiers in Immunology, vol. 10, p. 3, 2019.

Acknowledgments:

Versus Arthritis

Disclosure of Interests:

None declared

OP0217 INVOLVEMENT OF LARGE JOINTS AT DISEASE PRESENTATION IS ASSOCIATED WITH DIVERSE HISTOPATHOLOGICAL FEATURES AND CLINICAL OUTCOMES IN EARLY RHEUMATOID ARTHRITIS

Background:

The involvement of large joints at disease presentation in early Rheumatoid Arthritis (RA) has been associated with severe disease activity. At the same time, the clinical heterogeneity of RA is known to be mirrored by heterogeneity of synovial inflammation, with specific histological patterns (pathotypes) associated with treatment response and disease progression. However, it is not known whether joint size is associated with specific pathotypes.

Objectives:

To analyse histopathological features of synovial biopsies from joints of different sizes and establish the relationship with clinical outcomes in patients with early RA.

Methods:

167 patients with early (<1 year) treatment-naïve RA, fulfilling the 2010 RA criteria and recruited at Barts Health NHS Trust, underwent US-guided synovial biopsy of the most inflamed joint, either large (knee), medium (e.g. wrist, ankle, elbow) or small (MCPs, MTPs), before starting treatment with csDMARDS with a treat to target approach. Upon SQ scoring (0-4) of immune cell infiltration, tissues were classified into lympho-myeloid, diffuse-myeloid and pauci-immune pathotypes. Synovial samples from 111 patients underwent RNA-seq.

Results:

The majority of synovial biopsies were performed on medium and small joints (60.6% and 19.4%) as compared to 21.3% in large joints (Table 1). At baseline, patients who underwent large joint biopsy showed significantly higher levels of inflammation (CRP 27.9±32.4 large, 20.7±26.9 medium, 10.4±9.8 small, p=0.007) and higher HAQ (1.8 ± 0.7 large, 1.4 ± 0.8 medium, 1.2 ±0.9 small, p=0.012), with no differences in DAS28. Significantly higher inflammatory scores and higher proportion of lympho-myeloid pathotype were observed in large joints (Table 1 and Figure 1). 6 months after treat-to-target treatment with csDMARDs, large joints patients had significantly higher HAQ and lower response (RR for low disease activity in large vs medium joints 0.5, 95%CI 0.2-0.9, p=0.03). Finally, differentially expressed genes by RNA-seq showed segregation according to joint size (Figure 2), with upregulation of genes of the Homeobox transcription factors family in large joints.

Table 1.

EULAR 2010 RA (n=167)

Large joints#33 (19.4%)Medium joints#100 (60.6%)Small Joints#34 (20%)P*Clinical featuresESR mm/h,mean (SD)48.2 (31.5)39.6 (30.8)29.2 (17.3)nsCRP mg/L,mean (SD)27.9 (32.4)20.7 (26.9)10.4 (9.8)0.007DAS28, mean (SD)6 (1.2)5.7 (1.4)5.7 (1.5)nsHAQ, mean (SD)1.8 (0.7)1.4 (0.8)1.2 (0.9)0.012ACPA-positive, %70.9%77.3%83.9%nsRF-positive,%71.9%74.2%80.6%nsHistologyInflammatory score,median IQR)5 (3)4 (4)2 (2.75)<0.001Pathotype,%Ungraded6.1%7.8%2.9%0.014Fibroid6.1%24.3%32.3%Myeloid30.3%28.1%47.1%Lympho-myeloid57.6%39.8%17.6%Clinical outcomes at 6 monthsDAS28 6m,mean (SD)4.2 (1.8)3.4 (1.9)3.7 (1.5)nsHAQ 6m,mean (SD)1.2 (0.8)0.8 (0.8)0.8 (0.8)0.012DAS28 6m <3.2,%23.3%48.8%37.9%0.04

#Large joints: knees; Medium joints: wrists, ankle, elbows; Small joints: MCPs, MTPs, PIPs; * Chi-squared or Kruskal–Wallis as appropriate;

Conclusion:

Synovial biopsy of large joints as the most inflamed joints at disease presentation identified patients with early RA with specific histopathological features and clinical outcomes. Together with clustering of differentially expressed genes according to joint size, this suggests that the involvement of different joint compartments in early RA contributes to disease heterogeneity with potential physiopathological and clinical implications.

References:

[1]Humby et al Ann Rheum Dis. 2019 Jun;78(6):761-772

[2]Lewis et al Cell Rep. 2019 Aug 27;28(9):2455-2470.e5

[3]Linn-Rasker SP et al Ann Rheum Dis. 2007 May;66(5):646-50

Acknowledgments:

PEAChttp://www.peac-mrc.mds.qmul.ac.ukMRC grant 36661 & ARUK Grant 20022

F. Rivellese NIHR Fellowship TRF-2018-11-ST2-002

Disclosure of Interests:

None declared

Impulsivity, personality and bipolar disorder

Background

Increased impulsivity is a diagnostic feature of mania in bipolar disorder (BD). However it is unclear whether increased impulsivity is also a trait feature of BD and therefore present in remission. Trait impulsivity can also be construed as a personality dimension but the relationship between personality and impulsivity in BD has not been explored. The aim of this study was to examine the relationship of impulsivity to clinical status and personality characteristics in patients with BD.

Methods

We measured impulsivity using the Barratt Impulsiveness Scale (BIS-11) and personality dimensions using Eysenck Personality Questionnaire in 106 BD patients and demographically matched healthy volunteers. Clinical symptoms were assessed in all participants using the Clinical Global Impressions Scale, the Montgomery-Asberg Depression Rating Scale and the Young Mania Rating Scale. Based on their clinical status patients were divided in remitted (n = 36), subsyndromal (n = 25) and syndromal (n = 45).

Results

There was no difference in BIS-11 and EPQ scores between remitted patients and healthy subjects. Impulsivity, Neuroticism and Psychoticism scores were increased in subsyndromal and syndromal patients. Within the BD group, total BIS-11 score was predicted mainly by symptoms severity followed by Psychoticism and Neuroticism scores.

Conclusions

Increased impulsivity may not be a trait feature of BD. Symptom severity is the most significant determinant of impulsivity measures even in subsyndromal patients.

The relationship of impulsivity to response inhibition and decision-making in remitted patients with bipolar disorder

Background

Impulsivity, a core feature of bipolar disorder (BD), is a multifaceted concept encompassing failure of response inhibition and poor decision-making. Abnormalities in these two cognitive domains have been reported in BD patients but their relationship with impulsivity has not been explored.

Methods

Twenty-five remitted patients with BD completed the Barratt Impulsiveness Scale (BIS) and performed the Hayling Sentence Completion Task (HSCT) and a computerized version of the Iowa Gambling task. The HSCT total errors scaled score was used as a measure of response inhibition while the gabling task score, which reflects participants' ability to make advantageous choices, was used a measure of decision making.

Results

Higher scores on the BIS attentional and non-planning subscales were respectively associated with more errors in the HSCT and less advantageous choices in the gambling task.

Limitations

All patients were medicated. Healthy participants were not included.

Conclusions

Viewed in the context of recent relevant studies our findings suggest that impulsivity, response inhibition and decision-making in BD may represent behavioural manifestations of the same underlying biological mechanism possibly linked to ventral prefrontal cortical function.

Stratified primary care versus non-stratified care for musculoskeletal pain: findings from the STarT MSK feasibility and pilot cluster randomized controlled trial

BACKGROUND

Musculoskeletal (MSK) pain from the five most common presentations to primary care (back, neck, shoulder, knee or multi-site pain), where the majority of patients are managed, is a costly global health challenge. At present, first-line decision-making is based on clinical reasoning and stratified models of care have only been tested in patients with low back pain. We therefore, examined the feasibility of; a) a future definitive cluster randomised controlled trial (RCT), and b) General Practitioners (GPs) providing stratified care at the point-of-consultation for these five most common MSK pain presentations.

METHODS

The design was a pragmatic pilot, two parallel-arm (stratified versus non-stratified care), cluster RCT and the setting was 8 UK GP practices (4 intervention, 4 control) with randomisation (stratified by practice size) and blinding of trial statistician and outcome data-collectors. Participants were adult consulters with MSK pain without indicators of serious pathologies, urgent medical needs, or vulnerabilities. Potential participant records were tagged and individuals sent postal invitations using a GP point-of-consultation electronic medical record (EMR) template. The intervention was supported by the EMR template housing the Keele STarT MSK Tool (to stratify into low, medium and high-risk prognostic subgroups of persistent pain and disability) and recommended matched treatment options. Feasibility outcomes included exploration of recruitment and follow-up rates, selection bias, and GP intervention fidelity. To capture recommended outcomes including pain and function, participants completed an initial questionnaire, brief monthly questionnaire (postal or SMS), and 6-month follow-up questionnaire. An anonymised EMR audit described GP decision-making.

RESULTS

GPs screened 3063 patients (intervention = 1591, control = 1472), completed the EMR template with 1237 eligible patients (intervention = 513, control = 724) and 524 participants (42%) consented to data collection (intervention = 231, control = 293). Recruitment took 28 weeks (target 12 weeks) with > 90% follow-up retention (target > 75%). We detected no selection bias of concern and no harms identified. GP stratification tool fidelity failed to achieve a-priori success criteria, whilst fidelity to the matched treatments achieved "complete success".

CONCLUSIONS

A future definitive cluster RCT of stratified care for MSK pain is feasible and is underway, following key amendments including a clinician-completed version of the stratification tool and refinements to recommended matched treatments.

TRIAL REGISTRATION

Name of the registry: ISRCTN.

TRIAL REGISTRATION NUMBER

15366334. Date of registration: 06/04/2016.

Efficacy of electromotive drug administration in delivering botulinum toxin a in children with neuropathic detrusor overactivity-outcomes of a pilot study

BACKGROUND

Intravesical botulinum toxin A (BtA) injection is well established in managing paediatric neuropathic detrusor overactivity (NDO). Electromotive drug administration (EMDA) is a less invasive method, which can be performed in the clinic, using pulsed electrical current for drug delivery via a urethral catheter. Few small studies report good outcomes following BtA via EMDA (BtA/EMDA) into bladders of children with NDO.

OBJECTIVE

The objective of this study is to assess the efficacy of BtA/EMDA in children with NDO, reduced bladder capacity and compliance.

METHODS

Twelve children with NDO on baseline urodynamic study were prospectively included. Pre-BtA/EMDA and post-BtA/EMDA results compared the following four parameters: maximal cystometric capacity, bladder compliance, maximal detrusor pressure (pDetmax) during detrusor overactivity and pDetmax at capacity. The Wilcoxon matched-pairs signed-rank test using Graphpad Prism 8 was used for analysis. Secondary outcomes include adverse effects and symptomatic improvement.

RESULTS

Fourteen episodes of BtA/EMDA were performed. Five patients received 3.3 IU/kg of Botox®, and five received 10 IU/kg (maximum 300 IU). Four patients received 10 IU/kg of Dysport®. Two patients in the Dysport®/EMDA group also received Botox®/EMDA more than six months previously. Thirteen of 14 post-EMDA results were completed and included in the paired analysis. No statistically significant improvements in any cystometric parameters were demonstrated. Eight patients subsequently had intravesical BtA injections with significant improvements in both cystometric parameters and symptoms. Two patients subsequently transitioned to adult services; one was commenced on mirabegron, and one has undergone ileocystoplasty with Mitrofanoff appendicovesicostomy.

DISCUSSION

Despite some evidence to support BtA/EMDA in children with NDO, the authors were unable to replicate previously published positive cystometric and symptomatic outcomes. In addition, BtA/EMDA performed poorly when compared with conventional intravesical BtA injections. This implies failure of EMDA to deliver BtA correctly to the target tissue. The large size of the BtA molecule or the abnormal bladder wall in NDO could account for the negative results. Thorough preparation and consultation was undertaken before this study with BtA/EMDA, and it is discouraging that the authors were unable to reproduce the positive results of other groups.

CONCLUSIONS

Although safe and acceptable to most patients, the authors cannot recommend the use of BtA/EMDA for NDO in children at present.

Neurophysiological correlates of stereotypic behaviour in a model carnivore species

Stereotypic behaviour (SB) is common in animals housed in farm, zoo or laboratory conditions, including captive Carnivora (e.g. wild ursids and felids). Neurobiological data on housing-induced SBs come from four species (macaques, two rodent species, and horses), and suggest basal ganglia (BG) dysfunction. We investigated whether similar patterns occur in Carnivora via a model, American mink, because their SB is distinctive in form and timing. We raised 32 males in non-enriched (NE) or enriched (E) cages for 2 years, and assessed two forms of SB: 1) Carnivora-typical locomotor-and-whole-body ('loco') SBs (e.g. pacing, weaving); 2) scrabbling with the forepaws. Neuronal activity was analysed via cytochrome oxidase (CO) staining of the dorsal striatum (caudate; putamen), globus pallidus (externus, GPe; internus, GPi), STN, and nucleus accumbens (NAc); and the GPe:GPi ratio (GPr) calculated to assess relative activation of direct and indirect pathways. NE mink stereotyped more, and had lower GPr CO-staining indicating relatively lower indirect pathway activation. However, no single BG area was affected by housing and nor did GPr values covary with SB. Independent of housing, elevated NAc CO-staining predicted more loco SB, while scrabbling, probably because it negatively correlated with loco SB, negatively covaried with NAc CO-staining in NE subjects. These results thus implicate the NAc in individual differences in mink SB. However, because they cannot explain why NE subjects showed more SB, they provide limited support for the BG dysfunction hypothesis for this species' housing-induced SB. More research is therefore needed to understand how barren housing causes SB in captive Carnivora.

Detecting autoreactive B cells in the peripheral blood of people with type 1 diabetes using ELISpot

Type 1 diabetes mellitus (T1D) is an autoimmune disorder where T lymphocytes damage the islet beta cells but B lymphocytes also play an important role. Although changes in peripheral B cell phenotype have been observed, little is known about the B cells that secrete the autoantibodies. We developed a sensitive B cell enzyme-linked immunospot assay (ELISpot assay) to detect individual B cell antibody responses to glutamic acid decarboxylase (GAD) and islet antigen-2 (IA-2). We found that even healthy donors have B cells that secrete antibodies in response to GAD and IA-2 in the ELISpot. There was increased B cell reactivity to autoantigens in the peripheral blood of individuals with newly-diagnosed, but not long-standing, type 1 diabetes. However, no correlation with serum autoantibody levels was found, indicating that additional factors such as antigen affinity or exposure to antigens in vivo are required for antibody secretion, and that even healthy donors have potentially autoreactive B cells.

Impacting on factors promoting intra-group aggression in secure psychiatric settings

Three preliminary and linked studies investigate the impact of making alterations to factors considered relevant to engaging in and experiencing intra-group aggression (bullying) among adult male patients detained in a single secure forensic hospital. Study one (n = 44) outlines the institutional factors, attitudes towards bullying and environmental factors that increase the likelihood of engaging in bullying and/or being victimised. Study two (n = 53 patients and 167 staff) assesses the effect of three variations of intervention that aimed to reduce intra-group aggression through direct alteration of the physical and psychosocial environment, using data from both patients and staff. Study three (n = 414) looks at the effects of two variations of the intervention used in study two, which offered patients’ participation in individual and communal activities. It was predicted that changes to the physical and social environment would produce a reduction in the factors shown to predict intra-group aggression. Attitudes supportive of bullying and the presence of social hierarchies each increased the likelihood of engaging in bullying. Indirect changes to the social environment on the wards had more positive effects than those incorporating direct alterations to the physical and social environment. The differences in effectiveness of the two approaches are discussed in relation to the established predictors of intra-group aggression. The research concludes by noting the preliminary nature of the research and outlining potential directions for future research and intervention.

Onabotulinum toxin A in children with refractory idiopathic overactive bladder: medium-term outcomes

INTRODUCTION

Botulinum toxin-A (BtA) has been used for refractory idiopathic overactive bladder (IOAB) in children. Data on the optimum dose success rates, duration of effect, complications and medium-term outcomes are limited. This study aims to analyse the authors' experience to provide medium-term results of BtA in symptomatic refractory patients.

MATERIALS AND METHODS

Patients with refractory IOAB who were treated with BtA (Botox®) were retrospectively analysed. All patients had urodynamic study before treating with BtA. Group A had low-dose BtA (LDBtA) at 5 units/kg (maximum 150 units), and Group B had high-dose BtA (HDBtA) at 10 units/kg (maximum 300 Units). Post-BtA clinical response, functional bladder capacity (FBC) and postvoid residual (PVR) were assessed in addition to the duration of response.

RESULTS

Thirty-nine patients, 11 male and 28 female, were analysed. Forty-six percentage had symptom improvement (73% of males and 36% of females [P = 0.072, ns]). The difference in response rates between LDBtA and HDBtA was not statistically significant (P = 0.684). Increase in total bladder capacity (TBC) was greater in those given HDBtA (P ≤ 0.001), but the increase in FBC was not different between the groups, due to greater PVRs in the HDBtA group. Nine patients (23%) developed UTI; however, six of these patients suffered with UTI pre-BtA as well. Only three were asymptomatic after a single treatment with BtA. The remainder required further BtA or oral anticholinergic therapy. At a median follow-up of 35.4 months (interquartile range [IQR] 25.2-46.6), 12 (31%) were asymptomatic and off all therapy, 18 (46%) were still symptomatic despite therapy and 9 (23%) had their symptoms controlled on continuing treatment.

DISCUSSION AND CONCLUSIONS

Botulinum toxin-A improves symptoms in 46% of children after the first injection in refractory IOAB. Although HDBtA resulted in greater increase in bladder capacity, it conferred no advantage in terms of success rate or duration of response. Five units/kg may be an optimum dose to use as a first treatment with the understanding that some patients will require a higher dose. And, there will be a cohort of patients who need a dose lower than 5 units/kg. A higher dose is more likely to lead to PVR leading to urine stasis and UTIs. The success of BtA only lasts until its effect wears off, and the majority of this cohort (36/39) required continuing treatment with repeat BtA or anticholinergic agents. However, it remains a useful option in patients who are intolerant or unresponsive to anticholinergic medication with symptomatic resolution in 30% at medium-term follow-up.

Individually Specified Drug Immunoconjugates in Cancer Treatment

Forty-three patients with disseminated refractory malignancies each received an individually-specified combination of either Adriamycin (24 patients) or mitomycin-C (19 patients) conjugated murine monoclonal antibodies. Tumors were typed using a panel of antibodies with both immunohistochemistry and flow cytometry. Cocktails of up to six antibodies were selected based on binding greater than 80% of the malignant cells in the biopsy specimen. These monoclonal antibody cocktails were drug conjugated and administered intravenously.

Seventeen out of twenty-four patients had reactions to the administration of Adriamycin immunoconjugates, but these were tolerable in all but two patients. Fever, chills, pruritis and skin rash were by far the most common transitory reactions. All were well controlled with premedication. In several patients it was demonstrated that there was limited antigenic drift among various biopsies within the same patient over time. Up to 1 gram of Adriamycin and up to 5 grams of monoclonal antibody were administered. The limiting factor appeared to be a variable dissociation of active Adriamycin from the antibody which unpredictably caused hemopoietic depression.

Similar findings were noted in 19 patients with mitomycin-C conjugates. Thrombocytopenia at a 60mg dose of mitomycin-C in this schedule was dose limiting. Preliminary serological evidence suggests that the development of an IgM antibody which is specific against the mouse monoclonal antibody has the specificity and sensitivity to predict clinical reactions. These antibodies were quantitatively less in mitomycin-C patients.

Selected patients were re-treated. One patient with chronic lymphocytic leukemia had re-treatment on three occasions and demonstrated regression of peripheral lymph nodes. Two patients with breast carcinoma had definite improvement in ulcerating skin lesions and two patients with tongue carcinoma had shrinkage of their lesions. No responses were seen with mitomycin-C conjugates but binding was noted to tumors and colon with likely drug induced colitis seen after colon binding. This study demonstrates the feasibility and illustrates technical considerations in preparing drug immunoconjugate cocktails for patients with refractory malignancies.

Cocktail formulation and antibody delivery was accomplished. The major technical hurdle appears to be the selection of effective conjugation methods that can be used to optimally bind drugs to monoclonal antibodies for targeted cancer therapy.

The cardiopulmonary exercise test grey zone; optimising fitness stratification by application of critical difference

BACKGROUND

Cardiorespiratory fitness can inform patient care, although to what extent natural variation in CRF influences clinical practice remains to be established. We calculated natural variation for cardiopulmonary exercise test (CPET) metrics, which may have implications for fitness stratification.

METHODS

In a two-armed experiment, critical difference comprising analytical imprecision and biological variation was calculated for cardiorespiratory fitness and thus defined the magnitude of change required to claim a clinically meaningful change. This metric was retrospectively applied to 213 patients scheduled for colorectal surgery. These patients underwent CPET and the potential for misclassification of fitness was calculated. We created a model with boundaries inclusive of natural variation [critical difference applied to oxygen uptake at anaerobic threshold (V˙O2-AT): 11 ml O2 kg-1 min-1, peak oxygen uptake (V˙O2 peak): 16 ml O2 kg-1 min-1, and ventilatory equivalent for carbon dioxide at AT (V̇E/V̇CO2-AT): 36].

RESULTS

The critical difference for V˙O2-AT, V˙O2 peak, and V˙E/V˙CO2-AT was 19%, 13%, and 10%, respectively, resulting in false negative and false positive rates of up to 28% and 32% for unfit patients. Our model identified boundaries for unfit and fit patients: AT <9.2 and ≥13.6 ml O2 kg-1 min-1, V˙O2 peak <14.2 and ≥18.3 ml kg-1 min-1, V˙E/V˙CO2-AT ≥40.1 and <32.7, between which an area of indeterminate-fitness was established. With natural variation considered, up to 60% of patients presented with indeterminate-fitness.

CONCLUSIONS

These findings support a reappraisal of current clinical interpretation of cardiorespiratory fitness highlighting the potential for incorrect fitness stratification when natural variation is not accounted for.

Subthalamic nucleus pathology contributes to repetitive behavior expression and is reversed by environmental enrichment

Repetitive motor behaviors are common in neurodevelopmental, psychiatric and neurological disorders. Despite their prevalence in certain clinical populations, our understanding of the neurobiological cause of repetitive behavior is lacking. Likewise, not knowing the pathophysiology has precluded efforts to find effective drug treatments. Our comparisons between mouse strains that differ in their expression of repetitive behavior showed an important role of the subthalamic nucleus (STN). In mice with high rates of repetitive behavior, we found significant differences in dendritic spine density, gene expression and neuronal activation in the STN. Taken together, these data show a hypoglutamatergic state. Furthermore, by using environmental enrichment to reduce repetitive behavior, we found evidence of increased glutamatergic tone in the STN with our measures of spine density and gene expression. These results suggest the STN is a major contributor to repetitive behavior expression and highlight the potential of drugs that increase STN function to reduce repetitive behavior in clinical populations.