Non-physician endoscopists: A systematic review

Table 2 Assessment of the risk of bias assessments for studies included into this systematic review and key characteristics of data analysis

Publication	Sequence generation	Allocation concealment	Blinding of participants, personnel and outcome assessors	Incomplete outcome data	Selective outcome reporting	Other sources of bias	Study hypothesis and power calculation
Rosevelt[8], 1984	No randomization	No	No	Not specified	Likely, report was intended to describe a successful training program		No hypothesis, no statistics
Schroy et al[4], 1988	No randomization, review of videotape	No	No	Not specified	Report of an established service model. Review of videotapes Quality assurance		No statistics
DiSario[15], 1993	Computer generated randomization	Not specified	No	Not specified	Aim was to demonstrate that “.registered nurses could be trained to perform the flexible sigmoidoscopy in a similar to resident physicians’		Not powered to demonstrate equivalence, no formal power calculations
Maule[7], 1994	No randomization	Not specified	No	Not specified	The study was done to confirm that training of nurse endoscopists is feasible.		Hypothesis defined (no difference), no power calculation for equivalence study, oucome parameters not specified a priori
Moshakis et al[16], 1996	No randomization, no comparator	Not specified	No	Not specified	Report describes the successful training of one (1) nurse endoscopist		No hypotheses, no statistical analysis
Duthie et al[6], 1998	No randomization	No	No	Not specified	Evaluation of a training program that was developed and implemented by the authors (self-fulfilling prophecy)	Not evident	No hypothesis, no power calculation
Schoenfeld et al[17], 1999	No randomization, patients allocated to the ‘first available provider’	No	No	Not specified	No evidence	Not evident	Several outcome parameters specified, but no hypothesis tested, no power calculation for equivalence.
Schoenfeld et al[10], 1999	Randomization of veterans referred for flexible sigmoidoscopy. Computer generated randomization	No	unknown	Not specified	Justifies the implemented clinical service model.		Several outcome parameters listed, but no specific hypothesis, power calculation provided (to identify differences, but not targeting equivalence)
Wallace et al[9], 1999	No randomization, nurse-coordinator assigned eligible patients to a physician or non-physician endoscopists based upon ‘daily staffing assignments and patient time preference’	No	Unknown	Not specified	Justifies the implemented clinical service model.		No hypothesis stated, no power calculation
Schoen et al[26], 2000	No randomization	No	No	Not specified	Study targeted to demonstrate the good tolerability of flexible sigmoidoscopy	Gender distribution of patients was not equivalent across examiners, and the nurse practitioner did not have trainees working with her.	No hypothesis stated, no proper power calculation
Shapero et al[27], 2001	No randomization, allocation not clear	No	No	Not specified	Data justify the implemented clinical practice	Data are generated in the setting of CRC screening with flexible sigmoidoscopy, highly selective cohort.	Not done
Jain et al[28], 2002	No randomization	No	No	Not specified	Justification of implemented clinical practice	CRC screening utilizing flexible sigmoidoscopy, selective cohort	Not done
Meenan et al[29], 2003	No randomization	No	No	Not specified	Assessement of training progress		Not done
Smale et al[30], 2003	No randomization, part one retrospective analysis of endoscopy data base, second part prospective data collection	No	No	Not specified	Review and justification of clinical practice		Not done
Wildi et al[22], 2003	No randomization	No	No	Not specified	Sequential procedures Nurse endoscopist followed by physyician, potential effect of sequence.		Not done
Nielsen et al[12], 2005	No randomization	No	No	Not specified	Quality assurance of existing training program		Not done
Meining et al[3], 2007	No details in relation to the randomization process are provided. Patients unequally allocated to endoscopist or nurse	No	No	Reported but uneven numbers of ‘Randomization failures (33 vs 0). Considerable number of patients excluded (only 367 out of 641 reported)	Review and justification of clinical practice	Primary outcome parameter was stated as “appropriate diagnosis”, this outcome parameter was not reported.	Not done
Williams et al[19], 2006 Williams et al[21], 2009 Richardson et al[20], 2009	Randomization of patients to nurse or physician endoscopy	No	No	Properly reported	Primary outcome parameter not related to endoscopic. Measured with Gastrointestinal Symptoms Rating scale up to one year after procedure	Only patients suitable to be serviced by nurse endoscopists included. Numerically more patients from the nurse cohort were lost of follow-up without specified reasons (286 vs 269). A trend for more patients with weight loss in the physicians cohort, more patients in the physicians’’ cohort had previously barium enema (suggesting more chronic or relapsing symptoms)	Authors make reference to required sample sizes. Total number of patients completed was below the required sample size
Koornstra et al[11], 2009	It is stated that patients were randomly allocated, no information is given on allocation. Proportion of inpatients lower in the nurse group. No evidence for ethic approval or consent of patients. Training of nurse and medical staff was not identical	No	No	No information provided	Multiple endpoints reported	The authors developed a training program and with their data they aimed to confirm that their training program delivered (self-fulfilling prophecy).	Not powered to verify equivalence
Maslekar et al[31], 2010	Patients were allocated by administrative staff into the nurse or medical specialist group.	No	No	Incomplete response data cited as reason for exlusion (48/561 excluded), no intention to treat analysis	Study justifies an implemented service model that aims to address shortage of medical specialists	The instrument was unlikely to detect group differences. Variable mixture of flexible sigmoidoiscopy and colonoscopy across groups	No power calculation
Maslekar et al[32], 2010	No randomization	No information given	No	Not reported	Justifies implemented service and training model	For flexible sigmoidoscopies the validity of the endoscopists impression of maximal extension was tested. A priori unlikely to identify difference.	No power calculation
Shum et al[18], 2010	No randomizatiom, no comparator	No	No	No information provided	Justifies the implemented training model		No
Limoges-Gonzalez et al[44], 2011	It is stated that patients were randomly allocated, no information is given on allocation.	No	No	No information provided	Justifies the implemented service model	Postprocedure questionnaire was administered after (at least) 30 min of recovery. Drug effects likely to blunt potential differences	No power calculation
de Jonge et al[33], 2012	Routine quality data were used, no randomization.	No	No	No information provided	Data were partly retrospective data, partly prospective data, no justification given.	?	No power calculation
van Putten et al[34], 2012	Allocation of patients by secretatial staff, no randomization	No	Not reported	Not specified	Justifies and implemented service model	Significant differences in comorbidities (more severe in the Gastroenterologists group), differences in source of referral. Outcome assessment limited to immediate salary comparisons not total costs including pathology and follow-up.	No power calculation
Massl et al[5], 2013	It is stated that patients allocated by administrative staff, endoscopists assigned to lists randomly based on availability	No	No	79/2025 procedures not included due to drop out of 1 nurse endoscopist for unspecified reasons	Justifies the implemented service model	Patients younger than 18 years or referred for therapeutic procedures were excluded from the nurse endoscopist group only. Drop out of nurse endoscopist not justified.	Power calculation done.Appropriate numbers achieved.

Red cell = high risk of bias, yellow cell = unclear risk of bias, green cell = low risk of bias. CRC: Colorectal cancer.