Abstract: We identified no completed or ongoing RCTs, nRCTs, CBAs, or ITSs. No studies included people undergoing an epidural procedure. No studies compared different platelet count thresholds prior to a procedure. In this update we identified three retrospective cohort studies that contained participants who did and did not receive platelet transfusions prior to lumbar puncture procedures. All three studies were carried out in people with cancer, most of whom had a haematological malignancy. Two studies were in children, and one was in adults. The number of participants receiving platelet transfusions prior to the lumbar puncture procedures was not reported in one study. We therefore only summarised in a narrative form the relevant outcomes from two studies (150 participants; 129 children and 21 adults), in which the number of participants who received the transfusion was given. We judged the overall risk of bias for all reported outcomes for both studies as 'serious' based on the ROBINS-I tool. No procedure-related major bleeding occurred in the two studies that reported this outcome (2 studies, 150 participants, no cases, very low-quality evidence). There was no evidence of a difference in the risk of minor bleeding (traumatic tap) in participants who received platelet transfusions before a lumbar puncture and those who did not receive a platelet transfusion before the procedure (2 studies, 150 participants, very low-quality evidence). One of the 14 adults who received a platelet transfusion experienced minor bleeding (traumatic tap; defined as at least 500 x 106/L red blood cells in the cerebrospinal fluid); none of the seven adults who did not receive a platelet transfusion experienced this event. Ten children experienced minor bleeding (traumatic taps; defined as at least 100 x 106/L red blood cells in the cerebrospinal fluid), six out of the 57 children who received a platelet transfusion and four out of the 72 children who did not receive a platelet transfusion. No serious adverse events occurred in the one study that reported this outcome (1 study, 21 participants, very low-quality evidence). We found no studies that evaluated all-cause mortality within 30 days from the lumbar puncture procedure, length of hospital stay, proportion of participants who received platelet transfusions, or quality of life. We found no evidence from RCTs or non-randomised studies on which to base an assessment of the correct platelet transfusion threshold prior to insertion of a lumbar puncture needle or epidural catheter. There are no ongoing registered RCTs assessing the effects of different platelet transfusion thresholds prior to the insertion of a lumbar puncture or epidural anaesthesia in people with thrombocytopenia. Any future study would need to be very large to detect a difference in the risk of bleeding. A study would need to be designed with at least 47,030 participants to be able to detect an increase in the number of people who had major procedure-related bleeding from 1 in 1000 to 2 in 1000. The use of a central data collection register or routinely collected electronic records (big data) is likely to be the only method to systematically gather data relevant to this population.

Plain-language summary: We searched scientific databases for clinical studies of people of any age with low platelet counts requiring a lumbar puncture or epidural anaesthesia. The evidence is current to 13 February 2018. In this review, we found only three cohort studies. Only two of these studies reported outcomes relevant to this review. Both studies included people with low platelet counts and blood cancer; one included 21 adults and the other included 129 children. Both studies compared people who had and had not received platelet transfusions before the insertion of a lumbar puncture needle. No studies assessed the use of platelet transfusions prior to insertion of an epidural catheter or different platelet count thresholds for platelet transfusion administration prior to a procedure. There were no major procedure-related bleeding complications in either study. No serious adverse events occurred in the one study (21 participants) that reported this outcome. There was little or no difference in the number of minor bleeding complications in either adults or children who received or did not receive platelet transfusions. None of the studies reported on death, number of platelet transfusions given after the procedure, length of hospital stay, or quality of life. The quality of the evidence from the included studies was very poor. We found no evidence from randomised controlled trials to answer our review question. A study would need to be designed with at least 47,030 participants to be able to detect an increase in the number of people who had bleeding after lumbar puncture or epidural anaesthetic from 1 in 1000 to 2 in 1000. A study that uses routinely collected electronic medical records (big data) is likely to be the only study design that could answer our review question.