Inappropriate use of randomised trials to evaluate complex phenomena: case study of vaginal breech delivery

Department of Obstetrics and Gynaecology, University of British Columbia, BC Women's Hospital, Vancouver, BC, V6H 3V5 Canada.
BMJ (online) (Impact Factor: 16.38). 10/2004; 329(7473):1039-42. DOI: 10.1136/bmj.329.7473.1039
Source: PubMed
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    • "*Address correspondence to this author at the Australian Research Centre for Population Oral Health, School of Dentistry, The University of Adelaide , SA 5005, Australia; Tel: +61 8 8303 3292; Fax: +61 8 8303 4858; E-mail: While RCTs are generally considered as the " gold standard " for obtaining solid evidence on the effect of health care interventions, some have questioned their applicability to complex interventions [8] and to health promotion strategies in particular [9-11]. The latter tend to be complex and require a long follow-up that may exceed the attention span of participants, who do not have a problem in the first place. "
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    ABSTRACT: Severe early childhood caries (S-ECC) affects 17% of 2-3 year old children in South Australia impacting on their general health and well-being. S-ECC is largely preventable by providing mothers with anticipatory guidance. Randomised controlled trials (RCTs) are the most decisive way to test this, but that approach suffers from near inevitable loss to follow-up that occurs with preventative strategies and distant outcome assessment. We re-examined the results of an RCT to prevent S-ECC using sensitivity analyses and multiple imputation to test different assumptions about violation of random allocation (1%) and major loss to follow-up (32%). Irrespective of any assumptions about missing outcomes, providing expectant mothers with anticipatory guidance during pregnancy and in the child’s first year of life, significantly reduced the incidence of S-ECC at 20 months of age. However, the relative risk of S-ECC varied from 0.18 (95% confidence interval (CI): 0.06 – 0.52) to 0.70 (95% CI: 0.56 – 0.88). Also the ‘number needed to treat’ (NNT) to prevent one case of S-ECC varied 2.5-fold: from 8 to 20 women given anticipatory guidance. Multiple imputation provided a best estimate of 0.25 (95% CI: 0.11 – 0.56) for the relative risk and of 14 (95% CI: 10 – 33) for the number needed to treat. Avoiding loss to follow-up is crucial in any RCT, but is difficult with preventative health care strategies. Instead of abandoning randomisation in such circumstances, sensitivity analyses and multiple imputation can consolidate the findings of an RCT and add extra value to the conclusions derived from it.
    The Open Dentistry Journal 07/2010; 4:55-60. DOI:10.2174/1874210601004020055
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    • "They reported an incidence of 2.3% in the PVB group and 3.1% in the PCS group. These long-term results suggest that the short-term composite end-points for neonatal morbidity may be statistically significant, but clinically misleading (Kotaska 2004). The original publication led to an immediate change in both clinical practice (Rietberg et al. 2005) and professional guidelines (RCOG 2001; ACOG 2001). "
    Journal of Obstetrics and Gynaecology 09/2006; 26(6):491-4. DOI:10.1080/01443610600797186 · 0.60 Impact Factor
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    • "Studies into the effectiveness of manual therapy have, however, demonstrated inconsistent results. Randomised control trials are considered to have significant limitations when applied to complex conditions or when treatments are variable (Kotaska 2004). The lack of consistent results may thus partly be due to subgroups of patients having different responses to treatment (Grant 2002) as disorders of the cervical spine cannot at this point be grouped into functionally homogenous categories (National Health and Medical Research Council 2003), or to the difficulty in precisely controlling the intervention being applied. "
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    ABSTRACT: Physiotherapists often use within-session changes to provide a guide for refining treatment application. This study tested the validity of within-session changes as predictors of between-session changes for patients with neck pain receiving manual therapy treatment. A total of 70 pairs of treatments from 29 patients with sub-acute non-specific neck pain receiving manual therapy were assessed to determine the relationship between within-session and between-session changes in range of motion (ROM), pain intensity, and centralisation. Measurements were taken of ROM of the more limited direction on each axis of flexion, extension, lateral-flexion and rotation, and pain (intensity and location) before and after treatment. The same measurements were repeated before the following treatment. Regression analysis demonstrated that within-session change accounted for 26% to 48% of the variability in between-session change for ROM and six per cent for pain intensity. The proportion of the within-session change for ROM maintained between sessions ranged from 42% to 63% (95% CI 25% to 88%). The odds ratios for within-session improved/not improved categorisation to predict between-session category for ROM ranged from 2.5 (95% CI 0.6 to 4.3) to 21.3 (95% CI 10.1 to 96.1), for pain intensity 4.5 (95% CI 1.2 to 14.4) and for pain centralisation 9.2 (95% CI 2.2 to 38.7) indicating greater likelihood of between-session improvement after within-session improvement. The between-session results for most patients (71% to 83%) could be classified correctly by their within-session category. The results support the use of within-session changes in ROM, centralisation, and possibly pain intensity as predictors of between-session changes for musculoskeletal disorders of the cervical spine.
    The Australian journal of physiotherapy 02/2005; 51(1):43-8. DOI:10.1016/S0004-9514(05)70052-0 · 3.48 Impact Factor
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