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Table 1 Summary of included studies categorised on study outcomes

From: Effects of continuity of care on health outcomes among patients with diabetes mellitus and/or hypertension: a systematic review

Authors (year) Country Design N Agea Length (years) CoC measurement CoC cut-off Results
w/ Improvement w/o improvement
I. Health indicators
 Hanninen, Takala et al. (2001) [31] Finland Cross-sectional DM: 260  < 65 2 Single ph. Same ph. ≥ 2 years   HbA1c
BMI
 Overland, Yue et al. (2001) [32] Australia Prospective cohort DM: 479 Single GP: 59.9 (50.7–67.0)
Multiple GP: 54.0 (48.7–61.5)
0.5 Single ph. Single ph.   HbA1c
Blood pressure
Lipid profile
 Parchman and Pugh (2002) [33] United States Prospective cohort DM: 265 58.7 (9.7) 2 CoCI No cut-off HbA1c  
 Sherina, Teng et al. (2003) [49] Malaysia Cross-sectional DM: 166 59.2  < 1 UPCI Median   HbA1c
 Mainous, Koopman et al. (2004) [34] United States Prospective cohort DM: 1400 No summary 6 Usual ph./site by patient questionnaire w/ usual ph./site HbA1c Blood pressure
LDL
 Litaker, Ritter et al. (2005) [50] United States Retrospective cohort DM: 1448 No summary 1 Single ph. Same ph. for 1 year   HbA1c
Blood pressure
 Fisher, Sloane et al. (2007) [25] United States Retrospective cohort HT: 459 58.9 (14.8) 2 CoCI 0.40 (low/med)
0.67 (med/high)
  Blood pressure
 Gulliford, Naithani et al. (2007) [35] United Kingdom Prospective cohort DM: 193 65  < 1 Experienced CoC by patient questionnaire No cut-off   HbA1c
Blood pressure
BMI
 Salzman, Yuen et al. (2006) [30] United States Retrospective cohort HT: 287  ≥ 18 3 Single ph. Same ph. of last 5 visits   Blood pressure
 Dearinger, Wilson et al. (2008) [36] United States Retrospective cohort DM: 101 61.8 3 UPCI 0.45 (low/high) HbA1c Blood pressure
LDL
 Younge, Jani et al. (2012) [51] United States Retrospective cohort DM: 484  ≥ 18 2 MMCI Quartiles HbA1c
LDL
Blood pressure
 Hanafi, Abdullah et al. (2015) [27] Malaysia Retrospective cohort HT: 1060 62.0 (10.4) 1 UPCI No cut-off   Blood pressure
 Liao, Lin et al. (2015) [52] Taiwan Retrospective cohort DM: 89,428 53.7 (11.1) 10 UPCI (ph. & site) 1.0 in ph. (high)
1.0 in site (high)
 < 0.7 in both ph. & site (low)
Others (med)
Complications (CVD, PVD, renal diseases and others)
Hospitalisation
Mortality rate
 
 Lustman, Comaneshter et al. (2016) [42] Israel Retrospective cohort DM: 23,294 High UPCI: 61.1
Low UPCI: 59.7
2 UPCI 0.75 (low/high) Mortality rate
HbA1c
Blood pressure
Hospitalisation
LDL
 Chang, Chien et al. (2018) [53] Taiwan Retrospective cohort DM: 26,063 55.8 (12.0) 17 CoCI 0.43 (low/med)
0.80 (med/high)
Complication (ESRD)
Hospitalisation
 
 Jang, Choy et al. (2018) [54] South Korea Retrospective cohort DM: 3565 No summary 8 CoCI 0.75 (low/high) Complication (ESRD)  
 Khanam, Kitsos et al. (2019) [28] Australia Retrospective cohort HT: 37,425  ≥ 18 3.5 HHI 0.5 (low/med)
0.75 (med/high)
1 (max)
Blood pressure  
 Kim and Park (2019) [48] South Korea Case–control DM: 55,558 No death: 76.7 (7.0)
w/ death: 76.7 (7.1)
12 UPCI (site) Lowest vs highest by SAS Rank Mortality rate  
 Lee, Chun et al. (2019) [47] South Korea Retrospective cohort DM: 16,806  > 45 12 CoCI 0.75 (low/high) Complication (thyroid disorder)  
 Leniz and Gulliford (2019) [62] Chile Cross-sectional HT: 1252
DM: 418
 ≥ 15 2 Questionnaire No cut-off   HbA1c
Blood pressure
 Nam, Lee et al. (2019) [55] South Korea Case–control DM: 2373  ≥ 20 10 CoCI Median Complications (CVD, nephropathy and others)
Healthcare expense
 
 Sousa Santos, Tavares Bello et al. (2019) [46] Portugal Retrospective cohort DM: 100 Studied: 69.2 (10.6)
Control: 67.2 (10.4)
5 Single ph. Same ph. ≥ 5 years HbA1c Blood pressure
BMI
LDL
 Choi, Choi et al. (2020) [29] South Korea Retrospective cohort HT: 244,187  ≥ 20 11 CoCI 0.23, 0.36, 0.56 Complication (CVD)  
II. Service Utilisation
 Knight, Dowden et al. (2009) [56] Canada Retrospective cohort DM: 1143  ≥ 65 3 CoCI
UPCI
SECON
0.75 Hospitalisation  
 Hong, Kang et al. (2010) [10] South Korea Retrospective cohort HT: 858,927
DM: 268,220
HT: 71.5 (5.0)
DM: 70.6 (4.6)
4 CoCI 0.20 (low/med)
0.40 (med/high)
Hospitalisation
A&E attendance
 
 Lin, Huang et al. (2010) [37] Taiwan Retrospective cohort DM: 6476 58.8 (12.7) 5 UPCI 0.47 (low/med)
0.75 (med/high)
Long-term hospitalisation Short-term hospitalisation
 Liu, Doug et al. (2010) [57] United States Retrospective cohort DM: 3873 58.7 (58.3–59.1) 2 FCI (site) No cut-off A&E attendance  
 Chen and Cheng (2011) [13] Taiwan Retrospective cohort DM: 48,107 60.7 (11.3) 7 CoCI 0.47 (low/med)
0.86 (mid/high)
Hospitalisation
A&E attendance
Medication expense
Healthcare expense
 
 Robles and Anderson (2011) [7] United States Retrospective cohort HT: 5590 Low CoCI: 76.2
Intermediate: 75.7
High CoCI: 75.9
1 CoCI 0.106 (low/med)
0.236 (med/high)
  Medication expense
 Worrall and Knight (2011) [38] Canada Retrospective cohort DM: 305 74.3(6.7) 3 UPCI 0.75 (low/high) Mortality rate
Hospitalisation
 
 Chen, Tseng et al. (2013) [18] Taiwan Retrospective cohort DM: 11,299 55.7(11.3) 7 CoCI 0.22 (low/med)
0.44 (med/high)
Hospitalisation
A&E attendance
 
 Hong and Kang (2013) [39] South Korea Retrospective cohort DM: 68,469 53.6 (12.1) 4 CoCI 0.4, 0.6, 0.8, 1 Mortality rate
Hospitalisation
Healthcare expense
 
 Hussey, Schneider et al. (2014) [40] United States Retrospective cohort DM: 166,654  > 65 2 CoCI (ph./site) No cut-off Hospitalisation
A&E attendance
Complications (MI, renal diseases and others)
Healthcare expense
 
 Comino, Islam et al. (2015) [58] Australia Retrospective cohort DM: 20,433  ≥ 45 1.5 UPCI 0.80 Hospitalisation  
 Cho, Nam et al. (2016) [59] South Korea Retrospective cohort DM: 5163  ≥ 20 9 CoCI 0.2, 0.4, 0.6, 0.8, 1 Hospitalisation  
 Hsu, Chou et al. (2016) [41] Taiwan Retrospective cohort DM: 3757 No summary 7 CoCI Low, medium, high (= 1) A&E attendance  
 Nam, Cho et al. (2016) [26] South Korea Retrospective cohort HT: 3,460,700  ≥ 20 3 CoCI 0.75 (low/high) Hospitalisation  
 Pu and Chou (2016) [61] Taiwan Retrospective cohort HT: 331,506
DM: 82,181
HT:
w/ A&E: 71
No A&E: 66
DM:
w/ A&E: 69
No A&E: 65
2 CoCI HT:
0.46 (low/med)
0.82(med/high)
DM:
0.43 (low/med)
0.72(med/high)
A&E attendance  
 Van Loenen, Faber et al. (2016) [43] the Netherlands Cross-sectional DM: 45,082 No summary 3 ph. and patient questionnaires No cut-off   Hospitalisation
 Weir, McAlister et al. (2016) [44] Canada Prospective cohort DM: 285,231 53.0 (10.5) 7 UPCI 0.75 (low/high) Mortality rate
Hospitalisation
 
 Li (2019) [45] Taiwan Retrospective cohort DM: 4007 High CoCI: 61.1 (10.6)
Low CoCI: 60.8 (10.5)
High UPCI: 61.1 (10.6)
Low UPCI: 60.8 (10.5)
3 CoCI
UPCI
Median (low/high) Hospitalisation
A&E attendance
Mortality rate
 Chen and Cheng (2020) [60] Taiwan Retrospective cohort DM: 57,965 56.3 4 CoCI Tertiles Hospitalisation  
  1. HT Hypertension, DM Diabetes mellitus, ph. Physician, CoC Continuity of care, CoCI Continuity of care index, UPCI Usual provider continuity index, SECON Sequential continuity index, MMCI Modified modified continuity index, FCI Fragmentation of care index, HHI Herfindahl–Hirschman index, A&E Accident and emergency, HbA1c Haemoglobin A1c; “Blood pressure” refers to either systolic blood pressure, diastolic blood pressure and a combined target of the two, BMI Body mass Index; “Lipid profile” (unless specified) refers to either levels of low density lipoprotein, high density lipoprotein, cholesterol or triglyceride, LDL Low-density lipoprotein; “Complications” refers to (but not limited to) onset of cardiovascular disease, end-stage renal disease etc., ESRD End-stage renal disease, CVD Cardiovascular diseases, MI Myocardial infarction, w/ With, w/o Without, N Number
  2. aAge summary was extracted based on the availability of the information by the following order: mean (SD), median (interquartile range), median, mean or range