Re: Re:Re: Systematic review of prognosis in acute low back pain: danger of high publication bias
Pijak and Gazdik (1) initially claimed we missed four relevant
studies in our systematic review of prognosis of back pain (2). We
explained that three of the studies were not eligible and one was, in
fact, included in the review (3).
Pijak and Gazdik do not concede their error, but they do raise a new
objection (4). They contend that "inclusion of patients with longer
duration may be useful as it can provide more information regarding the
outcome". This ignores the possibility that survival cohorts could provide
seriously biased estimates of prognosis (5).
The cohort study of Croft et al (6) recruited a survival cohort of
patients presenting to general practice with low back pain but separately
reports data for the inception sub-cohort of patients with pain of <_1 week="week" or="or" _2-3="_2-3" weeks.="weeks." _73="_73" of="of" subjects="subjects" with="with" pain="pain" less="less" than="than" _3="_3" weeks="weeks" at="at" first="first" consultation="consultation" reported="reported" and="and" disability="disability" months="months" _64="_64" _12="_12" calculated="calculated" from="from" table="table" _5.="_5." this="this" is="is" consistent="consistent" our="our" conclusion="conclusion" that="that" typically="typically" persist="persist" for="for" long="long" periods="periods" it="it" suggests="suggests" the="the" low="low" average="average" levels="levels" are="are" due="due" to="to" in="in" a="a" large="large" proportion="proportion" patients.="patients." p="p"/> 1. Pijak MR, et al. Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 9 Aug 2003.
2. Pengel LHM, et al. Acute low back pain: systematic review of its
prognosis. BMJ 2003; 327:323.
3. Herbert RD, et al. Re: Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 11 Aug 2003.
4. Pijak MR, et al. Re:Re: Systematic review of prognosis in acute low
back pain: danger of high publication bias. BMJ.com, 12 Aug 2003.
5. Fletcher RH, et al. Clinical epidemiology: the essentials. Baltimore:
Williams & Wilkins, 1996.
6. Croft PR, et al. Outcome of low back pain in general practice: a
prospective study. BMJ 1998;316:1356-9.
Competing interests:
None declared
Competing interests:
No competing interests
19 August 2003
Rob D Herbert
senior lecturer
Liset HM Pengel, Chris G Maher, Kathy M Refshauge
School of Physiotherapy, University of Sydney, PO Box 170, Lidcombe NSW 1825, Australia
Rapid Response:
Re: Re:Re: Systematic review of prognosis in acute low back pain: danger of high publication bias
Pijak and Gazdik (1) initially claimed we missed four relevant
studies in our systematic review of prognosis of back pain (2). We
explained that three of the studies were not eligible and one was, in
fact, included in the review (3).
Pijak and Gazdik do not concede their error, but they do raise a new
objection (4). They contend that "inclusion of patients with longer
duration may be useful as it can provide more information regarding the
outcome". This ignores the possibility that survival cohorts could provide
seriously biased estimates of prognosis (5).
The cohort study of Croft et al (6) recruited a survival cohort of
patients presenting to general practice with low back pain but separately
reports data for the inception sub-cohort of patients with pain of <_1 week="week" or="or" _2-3="_2-3" weeks.="weeks." _73="_73" of="of" subjects="subjects" with="with" pain="pain" less="less" than="than" _3="_3" weeks="weeks" at="at" first="first" consultation="consultation" reported="reported" and="and" disability="disability" months="months" _64="_64" _12="_12" calculated="calculated" from="from" table="table" _5.="_5." this="this" is="is" consistent="consistent" our="our" conclusion="conclusion" that="that" typically="typically" persist="persist" for="for" long="long" periods="periods" it="it" suggests="suggests" the="the" low="low" average="average" levels="levels" are="are" due="due" to="to" in="in" a="a" large="large" proportion="proportion" patients.="patients." p="p"/> 1. Pijak MR, et al. Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 9 Aug 2003.
2. Pengel LHM, et al. Acute low back pain: systematic review of its
prognosis. BMJ 2003; 327:323.
3. Herbert RD, et al. Re: Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 11 Aug 2003.
4. Pijak MR, et al. Re:Re: Systematic review of prognosis in acute low
back pain: danger of high publication bias. BMJ.com, 12 Aug 2003.
5. Fletcher RH, et al. Clinical epidemiology: the essentials. Baltimore:
Williams & Wilkins, 1996.
6. Croft PR, et al. Outcome of low back pain in general practice: a
prospective study. BMJ 1998;316:1356-9.
Competing interests:
None declared
Competing interests: No competing interests