From analyses of individual patient data ( seven studies , 918 patients ) , we found baseline pain strongly associated with absolute , but not relative , MCID as patients with higher baseline pain needed larger pain reduction to perceive relief .
Conclusions The MCID in acute pain varied greatly between studies and was influenced by baseline pain , definitions of improved patients and study design .
Background The minimum clinical ly important difference ( MCID ) is used to interpret the clinical relevance of results reported by trials and meta-analyses as well as to plan sample sizes in new studies .
However , there is a lack of consensus about the size of MCID in acute pain , which is a core symptom affecting patients across many clinical conditions .
Reliability and validity of a visual analog scale for acute abdominal pain in the ED.
The objective of the study was to assess the validity and reliability of the  visual analog scale ( VAS )  in the measurement of acute abdominal pain , and to identify the minimum clinical ly significant difference in VAS scores among patients with acute abdominal pain . The study was undertaken in preparation for a r and omized clinical trial of opioid use in acute abdominal pain . A prospect i ve , observational cohort study of a convenience sample of patients presenting to 2 urban EDs with the chief complaint of acute abdominal pain was conducted . At time 0 and 1 minute later each subject indicated pain severity on a 100 mm VAS . This was repeated every 30 minutes for 2 hours . Patients were also asked to contrast their current pain severity with their pain in the preceding 30 minutes using one of 5 grade d verbal descriptors : " much less pain , " " little less pain , " " the same pain , " " little more pain , " and " much more pain . " Validity was assessed by performing an analysis of variance for linear trend on the association between the 5 categorical pain descriptors and change in VAS scores . Reliability was assessed using the intra-class correlation coefficient ( ICC ) between VAS scores taken 1 minute apart , supplemented by a Bl and -Altman analysis . The minimum clinical ly significant difference in pain was defined as the mean difference between sequential VAS scores obtained 30 minutes apart when the patient noted a " little less " or " little more " pain . Differences in VAS scores increased linearly as pain descriptors escalated from " much less " to " much more " pain ( P < .001 ) . Reliability was high , ICC = 0.99 [ 95%CI 0.989 to 0.992 ] for 0 and 1 minute VAS scores . The minimum clinical ly significant difference in acute abdominal pain was 16 mm ( 95 % CI 13 , 18 mm ) . VAS measures of acute abdominal pain are valid and reliable . The 95 % CI surrounding the minimum clinical ly significant difference of approximately 16 mm overlaps with the 95 % CI of minimum clinical ly significant difference of approximately 13 mm reported previously in traumatic and other types of acute pain . We conclude that the VAS is a method ologically sound instrument for quantitative assessment of acute abdominal pain and for detecting clinical ly important changes in such pain
From analyses of individual patient data ( seven studies , 918 patients ) , we found baseline pain strongly associated with absolute , but not relative , MCID as patients with higher baseline pain needed larger pain reduction to perceive relief .
Conclusions The MCID in acute pain varied greatly between studies and was influenced by baseline pain , definitions of improved patients and study design .
Background The minimum clinical ly important difference ( MCID ) is used to interpret the clinical relevance of results reported by trials and meta-analyses as well as to plan sample sizes in new studies .
However , there is a lack of consensus about the size of MCID in acute pain , which is a core symptom affecting patients across many clinical conditions .