Inter-Hospital Variability of Postoperative Pain after Tonsillectomy: Prospective Registry-Based Multicentre Cohort Study

Objectives
Although tonsillectomy is one of the most frequent and painful surgeries, the association between baseline and process parameters and postoperative pain are not fully understood.
Methods
A multicentre prospective cohort study using a web-based registry enrolled 1,527 women and 1,008 men aged 4 to 85 years from 52 German hospitals between 2006 and 2015. Maximal pain (MP) score the first day after surgery on a numeric rating scale (NRS) from 0 (no pain) to 10 (MP) was the main outcome parameter.
Results
The mean maximal pain score was 5.8±2.2 (median 6). Multivariable analysis revealed that female gender (Odds ratio [OR] = 1.33; 95% confidence interval [CI] = 1.12 to 1.56; p = 0.001), age <20 years (OR = 1.56; CI = 1.27 to 1.91; p<0.0001), no pain counselling (OR = 1.78; CI = 1.370 to 2.316; p<0.001), chronic pain (OR = 1.34; CI = 1.107 to 1.64; p = 0.004), and receiving opioids in recovery room (OR = 1.89; CI = 1.55 to 2.325; p<0.001) or on ward (OR = 1.79; CI = 1.42 to 2.27; p<0.001) were independently associated with higher experienced maximal postoperative pain (greater the median of 6). The effect of age on pain was not linear. Maximal pain increased in underage patients to a peak at the age of 18 to 20 years. From the age of ≥20 years on, maximal pain after tonsillectomy continuously decreased. Even after adjustment to all statistically important baseline and process parameters, there was substantial variability of maximal pain between hospitals with a heterogeneity variance of 0.31.
Conclusion
Many patients seem to receive insufficient or ineffective analgesia after tonsillectomy. Further research should address if populations at risk of higher postoperative pain such as females, younger patients or those with preexisting pain might profit from a special pain management protocol. Beyond classical demographical and process parameters the large variability between different hospitals is striking and indicates the existence of other unknown factors influencing postoperative pain after tonsillectomy.