In a recent paper [1], using machine learning methods, our research team developed a simplified version of the Inguinal Pain Questionnaire (IPQ) by Fränneby et al. [2] This psychometric tool is designed to measure postoperative pain and disability following hernioplasty to identify those suffering from chronic pain. In the simplified version of the IPQ (sIPQ), we reduced the number of items from 18 to 8. This reduction was specifically designed to decrease the time required for its completion and enable telephonic follow-up of postoperative patients abided by the ongoing COVID-19 pandemic. While the psychometric properties of the sIPQ were found to be almost identical to those of the original IPQ in its developing cohort, no validation of the score was done. Therefore, in this study, we assess the sIPQ psychometric properties in an independent patient cohort.

Following Lichtenstein inguinal hernioplasty, 25 patients were enrolled in the study. Their characteristics are presented in Table 1. This sample size was calculated following the same steps and results of our previous study as well as the recommendation of a subject-to-item ratio ≥ 2 [1, 3]. The IPQ and sIPQ were telephonically administered at 7 days and 28 days postoperatively. The order in which the scores were administered was randomized to avoid bias. The time required to complete the IPQ was 13 IQR 5 min, compared to 7 IQR 3 min for the sIPQ (p < 0.001 in a paired Wilcoxon-rank sum test). Afterwards, we compared the full score values against those of the sIPQ (Table 2). Spearman’s rank correlation between the full IPQ and the sIPQ was 0.792, p < 0.001. Cronbach’s alpha for the IPQ data was 0.70 (95% CI 0.60–0.77), while for the sIPQ was 0.68 (95% CI 0.58–0.80). The score’s temporal stability was assessed by calculating the Spearman’s rank correlation of 7- and 28-day measurements. For the IPQ, its temporal stability was 0.68 (95% CI 0.52–0.82, p < 0.001) and for the sIPQ, 0.54 (95% CI 0.41–0.71, p < 0.001). Finally, to obtain the intraclass correlation coefficient (ICC) between the scores, we standardized them by subtracting the mean score value from each individual value and dividing the resulting number by the standard deviation. In that way, pairwise mean-standardized value comparisons were performed. The type 3–2 ICC between scores was 0.97 (95% CI 0.94–0.98) (Fig. 1).

Table 1 Patient characteristics
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Table 2 Simplified inguinal pain questionnaire
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Fig. 1
figure 1

Psychometric evaluation of the scores. The full value of the Inguinal Pain Questionnaire (IPQ) and its simplified version (sIPQ) were compared. Although there was a significant difference in their absolute values, the change slope between 7- and 28-day measurements is similar for the IPQ (a, blue) and the sIPQ (a, red). The correlation between the score absolute values was 79.2% (p < 0.001) (b), while the intraclass correlation coefficient for their mean-standardized values was 97.0% (p < 0.001) as shown in a Bland–Altman plot (c) and an expected vs. observed values plot (d). The shaded areas in the figure panels represent 95% CI

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Taken together, our results demonstrate that the sIPQ has psychometric properties that are almost identical to those of the full IPQ, thereby adequately capturing pain and disability following hernioplasty. While other abbreviated forms of the IPQ exist [4], the sIPQ was developed using a rigorous statistical analysis in contrast to heuristically determining which items would be more clinically relevant. Furthermore, the sIPQ was also developed from patient’s data collected in the immediate and mediate postoperative period, rather than after several years after surgery. Some potential drawbacks of the sIPQ include the fact that it does not consider pre-operative pain (question 1 of the full IPQ), thus, failing to establish a pain baseline; and not considering other daily activities that may trigger pain and impact quality of life, except for sitting and standing. However, in our opinion, the most significant value that the sIPQ offers is enabling data collection in a consistent and abbreviated manner, thereby fostering its use for telemedicine. Consultations and surgical follow-up using virtual modalities during the COVID-19 pandemic has been found to be safe and effective and will likely be the norm for low-risk patients in the foreseeable future [5, 6]. Using validated, abbreviated, and refined tools can, therefore, make the data collection more efficient, allow for better telemedicine assessments, and the timely and correct identification of patients who may need in-person consultations.