Months
following spinal surgery for back pain, patients remember
their initial pain as worse than they rated it at the time,
reports a recent study in the journal Spine.
A research team, headed by Dr. Ferran Pellisé of Hospital
Vall d'Hebron, Barcelona, Spain, concluded that studies relying
on such after-the-fact ratings may overestimate the effectiveness
of spinal surgery in relieving chronic back pain.
The researchers studied before-and-after ratings made by 58
patients who underwent lumbar fusion surgery for chronic low
back pain. Before their operation, all patients completed
standard evaluations of back pain and related disability.
These prospective (“forward-looking”) ratings were compared
with retrospective (“backward-looking”) ratings made an average
of three years after surgery.
Patients consistently rated themselves worse than in their
original questionnaires, when recalling their preoperative
state. For example, on a simple 10-point scale, the patients’
original average pain rating was 7.0. On follow-up ratings,
the patients recalled their pain as being significantly worse,
with average rating of 8.2.
Based on the original ratings, surgery produced an average
pain reduction of 3.3 points on the 10-point scale. Yet, if
the recalled ratings were used, the average improvement would
have been 4.6 points. Similar patterns were noted for other
standard ratings of back pain and related disability.
Whether the time since surgery was shorter or longer, the
extent of patient recall bias did not differ significantly.
The ratings did not vary in any systematic way, so there was
no way to adjust for them statistically.
Retrospective studies – in which patients are asked to remember
and rate their state of health before treatment – are widely
used in medical research. Few prior studies, however, have
looked at how patients’ recollections measure up to actual
pretreatment ratings. The use of retrospective studies to
assess the results of spinal surgery has increased in recent
years.
Relying on such after-the-fact pain ratings may give the impression
that surgery for back pain is more effective than it actually
is, the new results suggest. “Our study shows that relying
on a patient’s recall of his or her preoperative status a
few months or years after surgery is not a valid method for
establishing baseline status when treating low back pain,”
Dr. Pellisé and colleagues concluded.
SOURCE: “Reliability of Retrospective Clinical Data to Evaluate
the Effectiveness of Lumbar Fusion in Chronic Low Back Pain.”
Pellise, Ferran MD; Vidal, Xavier MD, PhD; Hernandez, Alejandro
MD; Cedraschi, Christine PhD; Bago, Joan MD; Villanueva, Carlos
MD. Spine. 30(3):365-368, February 1, 2005.
