Completeness in the Swedish Fracture Register and the Swedish National Patient Register: An Assessment of Humeral Fracture Registrations

Figures & data

Figure 1 Flowchart of the study design and the assessment of the “true” number of acute humeral fractures at Sahlgrenska University Hospital in 2011–2012. The “true” number of fractures was defined by (a) all the fractures registered in both registers and (b) all the unique fractures registered in either register and verified by the medical records.

Table 1 Reasons for Registration in the National Patient Register

			Number	% of All Registrations (n. 2173)	% of Adjusted Registrations* (n. 1648)
Humeral fracture registration, actual fracture			1513	69.6	91.8
Re-admission	Re-registration at SUH during study period		317	14.6	Excluded
	Humeral fracture prior to study period	≤ 2 years prior to re-admission	186	8.6	Excluded
		≥ 2 years prior to re-admission	16	0.7	1.0
	Humeral fracture primarily treated at another Swedish orthopedic department		22	1.0	Excluded
	Humeral fracture sustained and primarily treated abroad		11	0.5	0.7
Non-humeral fracture registration			108	5.0	6.6
Total			2173

Note: *Adjustment algorithm used on NPR data for routine completeness calculation in the Swedish Fracture register.

Abbreviation: SUH, Sahlgrenska University Hospital.

Table 2 Calculated Completeness with Different Reference Data from the National Patient Register (NPR)

	Reference Data from the NPR	Number of Registrations	True Fractures Missing	Formula for Completeness	Completeness (%)
NPR	All registrations	2173	51	2173/(1324+849+51)	97.7
	True number of humeral fractures	1513	51	1513/(1324+189+51)	96.7
	Adjusted registrations in the NPR*	1648	51	1648/(1324+324+51)	97.0
SFR	All registrations	1375	189	1375/(1324+51+849)	61.8
	True number of humeral fractures	1375	189	1375/(1324+51+189)	87.9
	Adjusted registrations in the NPR*	1375	189	1375/(1324+51+324)	80.9

Note: *Adjustment algorithm used on NPR data for routine completeness calculations in the SFR.

Abbreviation: SFR, Swedish Fracture Register.

Table 3 Positive Predictive Value and Relationship to the True Number of Fractures (N. 1564) with Different Reference Data in the National Patient Register (NPR)

	Reference Data from the NPR	Number of Registrations	Number of Actual Fractures	Erroneous Registrations	Positive Predictive Value (PPV) %	Confidence Interval (95%) of PPV	Relationship to the True Number of Fractures (%)
NPR	All registrations	2173	1513	660	69.6	67.7–71.6	138.9
	True number humeral fractures	1513	1513	0	100	100–100	96.7
	Number of patients (unique PINs)	1852	1513	339	81.7	79.9–83.5	118.4
	Adjusted registrations in the NPR*	1648	1513	135	91.8	90.5–93.1	105.4
SFR	All registrations	1375	1375	0	100	100–100	87.9

Note: *Adjustment algorithm used on NPR data for routine completeness calculations in the Swedish Fracture register.

Abbreviation: PIN, personal identification number.

Figure 2 Calculation of completeness in the SFR (Swedish Fracture Register; attached counties) and NPR (National Patient Register) in 2016–2018 according to the adjustment algorithm.