Pain vs Comfort Scores After Caesarean Section
Pain vs Comfort Scores After Caesarean Section
After local Human Research Ethics Committee (LHREC) approval and trial registration (ANZCTR No: 12610000890033), 337 women presenting for routine anaesthetic follow-up after Caesarean section, between November 2010 and September 2011, in the largest tertiary referral centre for maternity care in South Australia were considered for eligibility. We excluded those who were not English speaking or who needed an interpreter, patients under 18 yr of age, and those who were deaf, had an intellectual disability, or had a history of chronic pain or opiate abuse. Two researchers (C.S.L.C., A.M.W.) were involved in eligibility assessments and interviewing women after their Caesarean section. The researchers worked independently in assessing the women, and for the purposes of this study. Each woman was assessed and interviewed by one of the researchers (C.S.L.C., A.M.W.) between 10 and 36 h after operation. All eligible patients had patient characteristic data recorded before being randomized prospectively, into either having their pain assessed using standard pain scores (Group P) or comfort scores (Group C), within 5 min of their planned postoperative research assessment. The randomization sequence was computer-generated in blocks of unspecified size in a 1:1 ratio to give a parallel group design. Allocation concealment was ensured by using consecutively numbered, opaque sealed envelopes. Subjects were blinded to group allocation, by being unaware of the nature of the intervention, but assessors were not. Written informed patient consent to take part in the study was obtained after the postoperative questioning was completed. Where informed patient consent was not obtained, responses were recorded in the case notes and acted upon as per usual care, without including the patient data in the study. The assessment of pain or comfort was performed in addition to our routine post-anaesthesia rounds.
After initial introductions, two types of questioning, frequently used by anaesthetists in our institution, were used to assess pain after Caesarean section (Table 1). Group P patients were asked the structured question, 'You have had a Caesarean section and I am interested in your pain from the surgical trauma. So, is it okay if I ask you some questions about your pain?' Women were then asked, 'Do you have any pain?' If the presence of pain was confirmed, patients were asked for the location of their pain. Women were then asked to quantify their postoperative pain, at rest and with movement, on a 0–10-point VNRS, where '0' was 'no pain' and '10' was 'the worst pain imaginable'. A VAS was also used, where one end of the scale was marked, 'least pain' and the other, 'most pain'. On the reverse side of the VAS was a 0–100 mm scale (Fig. 1a). Women were then asked 'Does the wound bother you?', 'How much does it bother you, where "0" is no bother and "10" is the most bothersome imaginable?', 'Are you comfortable?', and 'Would you like additional pain relief?'
(Enlarge Image)
Figure 1.
VAS for comfort and for pain. (a) Pain VAS: diagram shows both front and back sides of the sliding scale. The diamond shape slides along the scale, used to indicate patient's pain level. (b) Comfort VAS (diagram shows both front and back sides of the sliding scale). The diamond shape slides along the scale, used to indicate patient's comfort level.
Women in Group C were asked the structured question, 'You have had your Caesarean section, your wound is healing and you're in the process of recovery. Is it okay if I ask you some questions about your level of comfort?', followed by 'Are you comfortable?' The researcher documented any reason for discomfort. They were then asked, for both at rest and on movement, 'Can you rate your comfort level where, "10" is the most comfortable and, "0" is the least comfortable?' They were then asked to quantify their comfort level on a VAS, where one end of the scale was marked as 'most comfort' and the other end was marked 'least comfort'. On the reverse side of the VAS was a 0–100 mm scale (Fig. 1b). Women were also asked 'Does the healing wound bother you?', 'How much does it bother you, where "0" is no bother and "10" is the most bothersome imaginable?', 'Do you have pain?', and 'Would you like additional analgesia?'
All women were asked: 'Do you think that the sensations that you have had after your operation to be unpleasant or not particularly unpleasant?', 'Do you prefer to be asked about your comfort level or your pain level, and why?' Lastly, study participants were asked, 'Do you think of the sensations after your operation to be that of "tissue damage" or "healing and recovery"?'. These questions were asked with the options presented in a computer-generated randomized sequence stratified according to Group P or C. For example, half the women in Group P and half the women in Group C were either asked whether they found the '… sensations to be those of tissue damage or healing and recovery' or '… sensations to be those of healing and recovery or tissue damage?' (Table 1).
Our primary outcome was to assess pain severity as measured by a 0–10-point VNRS for pain compared with an equivalent inverted VNRS for comfort. Our secondary outcomes included patient reports of: pain severity as measured by a VAS for pain compared with VAS for comfort; whether the surgical wound was bothersome or unpleasant; the level of bother as measured by a 0–10-point scale, where '0' is no bother and '10' is the most bothersome; whether the patient required additional analgesia; whether the patient preferred to be asked about their comfort level or pain level; and whether the patient considered the postoperative wound to be injury and disability or healing and recovery. Ongoing follow-up and postoperative management of all patients took place as per usual practice.
We used the mean and standard deviation estimates from pilot data of inverted VAS for comfort or VAS for pain assessments in 18 postoperative women. We calculated that to show a clinically relevant difference of 20 mm between pain and comfort groups, sample sizes of 137 and 114 participants/group were required, at rest and with movement, respectively, to give the study a power of 80% with an α=0.05. We assumed equivalence for our primary outcome VNRS as shown in several previous studies and planned to recruit 150 women/group to accommodate for unforeseen losses of data or participant withdrawals from the study.
Additional outcome data regarding urgency of Caesarean section, intraoperative blood loss, Apgar scores, and, admissions to the neonatal unit were collected from our hospital's clinical information service. All outcome data were transcribed onto a computerized spreadsheet (Excel™) and analysed according to the intention to treat (ITT) principle. Comfort scale data were flipped so as to assess the degree of discomfort with the standard measures of VNRS and VAS for pain. Dichotomous outcomes were reported as relative risk (RR) with 95% confidence intervals (95% CI). Non-parametric VNRS data and patient characteristic data were analysed using the Kruskal–Wallis test.
Methods
After local Human Research Ethics Committee (LHREC) approval and trial registration (ANZCTR No: 12610000890033), 337 women presenting for routine anaesthetic follow-up after Caesarean section, between November 2010 and September 2011, in the largest tertiary referral centre for maternity care in South Australia were considered for eligibility. We excluded those who were not English speaking or who needed an interpreter, patients under 18 yr of age, and those who were deaf, had an intellectual disability, or had a history of chronic pain or opiate abuse. Two researchers (C.S.L.C., A.M.W.) were involved in eligibility assessments and interviewing women after their Caesarean section. The researchers worked independently in assessing the women, and for the purposes of this study. Each woman was assessed and interviewed by one of the researchers (C.S.L.C., A.M.W.) between 10 and 36 h after operation. All eligible patients had patient characteristic data recorded before being randomized prospectively, into either having their pain assessed using standard pain scores (Group P) or comfort scores (Group C), within 5 min of their planned postoperative research assessment. The randomization sequence was computer-generated in blocks of unspecified size in a 1:1 ratio to give a parallel group design. Allocation concealment was ensured by using consecutively numbered, opaque sealed envelopes. Subjects were blinded to group allocation, by being unaware of the nature of the intervention, but assessors were not. Written informed patient consent to take part in the study was obtained after the postoperative questioning was completed. Where informed patient consent was not obtained, responses were recorded in the case notes and acted upon as per usual care, without including the patient data in the study. The assessment of pain or comfort was performed in addition to our routine post-anaesthesia rounds.
After initial introductions, two types of questioning, frequently used by anaesthetists in our institution, were used to assess pain after Caesarean section (Table 1). Group P patients were asked the structured question, 'You have had a Caesarean section and I am interested in your pain from the surgical trauma. So, is it okay if I ask you some questions about your pain?' Women were then asked, 'Do you have any pain?' If the presence of pain was confirmed, patients were asked for the location of their pain. Women were then asked to quantify their postoperative pain, at rest and with movement, on a 0–10-point VNRS, where '0' was 'no pain' and '10' was 'the worst pain imaginable'. A VAS was also used, where one end of the scale was marked, 'least pain' and the other, 'most pain'. On the reverse side of the VAS was a 0–100 mm scale (Fig. 1a). Women were then asked 'Does the wound bother you?', 'How much does it bother you, where "0" is no bother and "10" is the most bothersome imaginable?', 'Are you comfortable?', and 'Would you like additional pain relief?'
(Enlarge Image)
Figure 1.
VAS for comfort and for pain. (a) Pain VAS: diagram shows both front and back sides of the sliding scale. The diamond shape slides along the scale, used to indicate patient's pain level. (b) Comfort VAS (diagram shows both front and back sides of the sliding scale). The diamond shape slides along the scale, used to indicate patient's comfort level.
Women in Group C were asked the structured question, 'You have had your Caesarean section, your wound is healing and you're in the process of recovery. Is it okay if I ask you some questions about your level of comfort?', followed by 'Are you comfortable?' The researcher documented any reason for discomfort. They were then asked, for both at rest and on movement, 'Can you rate your comfort level where, "10" is the most comfortable and, "0" is the least comfortable?' They were then asked to quantify their comfort level on a VAS, where one end of the scale was marked as 'most comfort' and the other end was marked 'least comfort'. On the reverse side of the VAS was a 0–100 mm scale (Fig. 1b). Women were also asked 'Does the healing wound bother you?', 'How much does it bother you, where "0" is no bother and "10" is the most bothersome imaginable?', 'Do you have pain?', and 'Would you like additional analgesia?'
All women were asked: 'Do you think that the sensations that you have had after your operation to be unpleasant or not particularly unpleasant?', 'Do you prefer to be asked about your comfort level or your pain level, and why?' Lastly, study participants were asked, 'Do you think of the sensations after your operation to be that of "tissue damage" or "healing and recovery"?'. These questions were asked with the options presented in a computer-generated randomized sequence stratified according to Group P or C. For example, half the women in Group P and half the women in Group C were either asked whether they found the '… sensations to be those of tissue damage or healing and recovery' or '… sensations to be those of healing and recovery or tissue damage?' (Table 1).
Our primary outcome was to assess pain severity as measured by a 0–10-point VNRS for pain compared with an equivalent inverted VNRS for comfort. Our secondary outcomes included patient reports of: pain severity as measured by a VAS for pain compared with VAS for comfort; whether the surgical wound was bothersome or unpleasant; the level of bother as measured by a 0–10-point scale, where '0' is no bother and '10' is the most bothersome; whether the patient required additional analgesia; whether the patient preferred to be asked about their comfort level or pain level; and whether the patient considered the postoperative wound to be injury and disability or healing and recovery. Ongoing follow-up and postoperative management of all patients took place as per usual practice.
Study Power
We used the mean and standard deviation estimates from pilot data of inverted VAS for comfort or VAS for pain assessments in 18 postoperative women. We calculated that to show a clinically relevant difference of 20 mm between pain and comfort groups, sample sizes of 137 and 114 participants/group were required, at rest and with movement, respectively, to give the study a power of 80% with an α=0.05. We assumed equivalence for our primary outcome VNRS as shown in several previous studies and planned to recruit 150 women/group to accommodate for unforeseen losses of data or participant withdrawals from the study.
Additional outcome data regarding urgency of Caesarean section, intraoperative blood loss, Apgar scores, and, admissions to the neonatal unit were collected from our hospital's clinical information service. All outcome data were transcribed onto a computerized spreadsheet (Excel™) and analysed according to the intention to treat (ITT) principle. Comfort scale data were flipped so as to assess the degree of discomfort with the standard measures of VNRS and VAS for pain. Dichotomous outcomes were reported as relative risk (RR) with 95% confidence intervals (95% CI). Non-parametric VNRS data and patient characteristic data were analysed using the Kruskal–Wallis test.
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