The two coprimary outcomes include the proportions of participants with at least 30% reduction in the IPSS total score from baseline at weeks 8 and 20.

Secondary outcomes will be measured by a range of tools, including the IPSS total score and subscales of voiding, storage and numbers of nocturia, the IPSS QoL, the BPH Impact Index (BPH-II) and hours of undisturbed sleep (HUS) at weeks 4, 8, 12, 20 and 32; the International Index of Erectile Function 5 (IIEF-5), the Hospital Anxiety and Depression Scale (HADS) and the Patient Global Index of Improvement (PGI-I) at weeks 8, 20 and 32. The volume of the prostate and PVR urine, maximum and average flow rate will also be measured at week 8 (figure 2). The secondary outcome measures and the time frame are shown in table 1.

Secondary outcome measures

The IPSS is a 7-item, reliable, valid and sensitive questionnaire that is commonly used to assess the severity of LUTS, including filling (urgency, frequency and nocturia) and voiding (incomplete emptying, intermittency, straining and weak urinary stream) symptoms.20–22 The score of IPSS ranges from 0 to 35, with scores of 0–7 indicating mild symptoms; 8–19 indicating moderate symptoms and 20–35 indicating severe symptoms.22 It has been established that a decrease of at least three points is the minimal clinically important difference,23 while a 30% reduction in the IPSS total score is the minimal clinical improvement recommended by the US Food and Drug Administration (FDA) for device therapy.24

The IPSS QoL includes only one specific question: if you are to spend the rest of your life with your urinary condition just the way it is now, how would you feel about that? The response is categorised into seven levels, with a score ranging from 0 to 6, and higher scores indicating poorer QoL. Despite its simplicity, this question is strongly associated with the overall symptom score.25

The BPH-II is a 4-item, self-administered tool that measures the interference of LUTS in participants’ physical, mental and usual activities over the past month. The score of BPH-II ranges from 0 to 13, with higher scores indicating greater BPH symptom-related impact.26

The IIEF-5 is an abridged, 5-item instrument for evaluating erectile function, ranging from 1 to 25 (normal, 22–25; mild, 17–21; mild to moderate, 12–16; moderate, 8–11 or severe, 1–7).27 28

The HUS is defined as the duration from falling asleep till awake in the morning, or till the first nocturia if any.29

The HADS is developed to quantify psychological distress, consisting of two 7-item subscales, one for anxiety and one for depression. The total score ranges from 0 to 42, with higher scores indicating worse conditions.30

The PGI-I evaluates the overall treatment effect as perceived by the participants themselves. The change can be rated in seven levels, including ‘very much better’, ‘much better’, ‘a little better’, ‘no change’, ‘a little worse’, ‘much worse’ or ‘very much worse’.31

To assess participants’ expectations of improvement in LUTS, participants will be asked: how do you expect the LUTS to be in 8 weeks at baseline. To assess participants’ belief of EA, at both baseline and week 8, participants will be asked: do you think that EA may be beneficial in treating your BPH?

Participants will be informed that there is a 50% chance of being allocated to receive either the traditional EA with deeper needling or the SA with shallower needling. After the last session at week 8, each participant will be asked whether they have received traditional EA, with the option of ‘Yes’ or ‘No’.

To ensure the consistency, personnel in each recruitment centre will receive extensive training from the principal investigator (ZL) on details of the protocol.

All treatments for each participant will be completed by 1–2 specific acupuncturists. In addition, one assessor must maintain responsibility for the same participants throughout the trial. They will explain the contents of handbook, if necessary, as well as remind the participants of their schedule through either phone or WeChat. At each assessment visit, the data will be collected and recorded in the paper case report form (CRF) promptly by assessors. The clinical research coordinators will type the data into the electronic data capture (EDC) system within 1 week. The clinical research associates (CRA) will supervise weekly through the system to enhance the quality. All data on the EDC system will be locked on verification of consistency between data online and the paper CRFs by two independent CRAs.

All deviations from the study protocol will be reported in time. Participants who withdraw or drop out will be documented during the trial. Lnkmed Tech Co. (Beijing, China) will be responsible to conceal the treatment allocation, which will only be revealed after the statistical analysis is completed.