Table 3

Summary of drug code changes within the 1998–2016 prescribing datasets, also separated by (current) chapter. Chapter names can be found in table 2

	BNF code change					No product match	No chemical match	Grand total
	Chapter	Section	Paragraph	Sub paragraph	No change	No product match	No chemical match	Grand total
Distinct count of drug name	94	52	560	203	21 258	815	293	23 275
% of drugs	0.40%	0.22%	2.41%	0.87%	91.33%	3.50%	1.26%	100%
% of items	0.04%	0.01%	0.84%	0.51%	97.67%	0.84%	0.10%	100%