Opioid drugs, including hydromorphone, are commonly used to treat neuropathic pain,
and are considered effective by some professionals. Most reviews have examined all
opioids together. This review sought evidence specifically for hydromorphone, at any
dose, and by any route of administration. Other opioids are considered in separate
reviews. This review is part of an update of a previous review, Hydromorphone for
acute and chronic pain that was withdrawn in 2013 because it needed updating and
splitting to be more specific for different pain conditions. This review focuses only
on neuropathic pain. To assess the analgesic efficacy of hydromorphone for chronic
neuropathic pain in adults, and the adverse events associated with its use in clinical
trials. We searched the Cochrane Central Register of Controlled Trials (CENTRAL),
via the CRSO; MEDLINE via Ovid; and EMBASE via Ovid from inception to 17 November
2015, together with reference lists of retrieved papers and reviews, and two online
study registries. We included randomised, double‐blind studies of two weeks' duration
or longer, comparing hydromorphone (at any dose, by any route of administration, or
in any formulation) with placebo or another active treatment in chronic neuropathic
pain. Two review authors independently searched for studies, extracted efficacy and
adverse event data, and examined issues of study quality. We did not carry out any
pooled analyses. We assessed the quality of the evidence using GRADE (Grading of Recommendations
Assessment, Development and Evaluation). Searches identified seven publications relating
to four studies. We excluded three studies. One post hoc (secondary) analysis of a
study published in four reports assessed the efficacy of hydromorphone in neuropathic
pain, satisfied our inclusion criteria, and was included in the review. The single
included study had an enriched enrolment, randomised withdrawal design with 94 participants
who were successfully switched from oral morphine to oral hydromorphone extended release
(about 60% of those enrolled). These participants were then randomised to continuing
hydromorphone for 12 weeks or tapering down the hydromorphone dose to placebo. The
methodological quality of the study was generally good, but we judged the risk of
bias for incomplete outcome data as unclear, and for study size as high. Since we
identified only one study for inclusion, we were unable to carry out any analyses.
The included study did not report any of our prespecified primary outcomes, which
relate to the number of participants achieving moderate or substantial levels of pain
relief. It did report a slightly larger increase in average pain intensity for placebo
in the randomised withdrawal phase than for continuing with hydromorphone. It also
reported the number of participants who withdrew due to lack of efficacy in the randomised
withdrawal phase, which may be an indicator of efficacy. However, in addition to using
an enriched enrolment, randomised withdrawal study design, there was an unusual choice
of imputation methods for withdrawals (about 50% of participants); the evidence was
of very low quality and inadequate to make a judgement on efficacy. Adverse events
occurred in about half of participants with hydromorphone, the most common being constipation
and nausea. A similar proportion of participants experienced adverse events with placebo,
the most common being opioid withdrawal syndrome (very low quality evidence). Most
adverse events were mild or moderate in intensity. One in eight participants withdrew
while taking hydromorphone during the conversion and titration phase, despite participants
being opioid‐tolerant (very low quality evidence). We downgraded the quality of the
evidence to very low because there was only one study with few participants, it did
not report clinically useful efficacy outcomes, and it was a post hoc analysis. There
was insufficient evidence to support or refute the suggestion that hydromorphone has
any efficacy in any neuropathic pain condition. Hydromorphone for neuropathic pain
in adults Bottom line There is no good evidence to support or refute the suggestion
that hydromorphone works in any neuropathic pain condition. Background Neuropathic
pain is pain coming from damaged nerves. It is different from pain messages that are
carried along healthy nerves from damaged tissue (for example, a fall or cut, or arthritic
knee). Neuropathic pain is often treated by different medicines (drugs) to those used
for pain from damaged tissue, which we often think of as painkillers. Medicines that
are sometimes used to treat depression or epilepsy can be very effective in some people
with neuropathic pain. But sometimes opioid painkillers are used to treat neuropathic
pain. Opioid painkillers are drugs like morphine. Morphine is derived from plants,
but many opioids are also made by chemical synthesis rather than being extracted from
plants. Hydromorphone is one of these synthetic opioids. It is available in numerous
countries for use as a painkiller, and can be given by mouth or by injection. This
review is part of an update of a previous review, Hydromorphone for acute and chronic
pain that was withdrawn in 2013 because it needed updating and splitting to be more
specific for different pain conditions. This review focuses only on neuropathic pain.
Study characteristics In November 2015, we searched for clinical trials where hydromorphone
was used to treat neuropathic pain in adults. We found one small study that did this
and met our requirements for the review. The study had a complicated design. Only
a minority of participants had neuropathic pain, with only 94 in the comparison with
placebo. Important pain outcomes were not reported. Key results The study provided
no convincing evidence of any benefit for hydromorphone over placebo. Of those people
who started taking hydromorphone, one in eight stopped because of side effects in
the first part of the study. The most common side effects were constipation and nausea,
which are typically experienced with opioids. Quality of the evidence We rated the
quality of the evidence as very low because of the study design, poor reporting of
important outcomes, and small numbers of participants. Very low quality evidence means
that we are very uncertain about the results.